Two hay fever pills to be exact but enough to tarnish his name forever.
The pills which he took prior to Scotland's World Cup match against Peru in 1978, contained a compound called Reactivan - a banned substance on Fifa's list.
A pity really because he was a skilful left-winger with a bag of tricks and a turn of pace which could leave many full-backs for dead - even into his late 30s when many players are meant to be 'past their best'.
A man who liked to entertain and please the crowd with various antics - but that was always set against a volatile temperament that saw him get more bookings than Elvis at Las Vegas.
Not to mention being the recipient of more than 20 red cards.
Many in blazers and ties would 'tut-tut' at this 'ruffian' and waffle on about the 'bad example being set to children'.
Like the bland boring types of today's football scene are setting a good one by doing zilch to ingratiate themselves to those who wish to one day be in their shoes?
Give me a 'bad example' any day of the week - at least you'll be left with something to talk about.
Before football clubs splashed out on PR machines to make sure that their players could be controlled to the point of limited accessibility and spewing out the same, dull regurgitated message ("the lads are looking forward to getting three points" etc zzzzzzzzzzzzz), footballers once related to those who filled their wage pockets.
George Best was one, Jimmy Greaves another, as was Alan Ball. Johnston was of that cloth.
Yes at times he didn't help himself with one disciplinary error after another.
But given the era he played in - defenders were given license to knock seven colours of the proverbial out of strikers and wingers by myopic referees - perhaps some mitigation is due his way?
Johnston joined Rangers in his teens and it was a decision by those at Ibrox that led him to become the player that he was renown for - even if he hated what was done at the time. He told The Herald back in 2003:
"I was actually what you would call the classical inside-forward but they changed me into a winger.
"When I went to Rangers in '62 they discovered I had speed and they stuck me out wide. I tell you, I hated it. You went ages without seeing the ball."
The players at Ibrox were stars in their own right - although Johnston had a wee issue with the 'know your place' attitudes' displayed by some. As he elaborates in the same Herald interview mentioned earlier:
"There was also a terrible clique at Rangers at the time and with all these great players - Ralph Brand, Bobby Shearer, Eric Caldow, and others - you had to go around referring to everyone as 'Mister'. I found it very hard"
Although this was a friendship that management tried to steer their young prospect away from - especially when money was involved.
Following a League Cup final triumph in 1964 when Rangers beat Celtic 2-1, the bonus wage packets were handed out to the victorious squad.
The bonus was meant to be £500 per player but Johnston opened his envelope to find his only contained £50.
Baxter told him straight away to head up to boss Scott Symon's office to get the remaining £450 that he was due.
This would be a daunting prospect for a young footballer. The manager's office at Ibrox apparently had a light outside of it.
If it was red, you waited your turn. Once it went green, then you took your life and career into your own hands and try to persuade your employer to let you have a couple of farthings.
Of this encounter, Johnston told The Scotsman last year:
“I didn’t have Baxter’s balls, not then, so I was quaking when the light went green. ‘Er, Boss, I think you might have made a wee mistake’.
"Symon flicked my shoulders and sorted my tie. ‘Now, now, Billy, you’re a young boy, just starting out. Don’t be impressed by the money you see flying around downstairs – these are card-school losers settling their debts. Behave yourself and your time will come. And don’t listen to Baxter’!"
Johnston would be a regular in Symon's team appearances in the dark blue were few and far between.
His disciplinary record might have had something to do with that.
By 1970 he had already racked up five sending offs and a total of 105 days of being banned by the SFA.
Not to mention the cheeky attitude he brought onto the park which he saw as 'delivery entertainment' while the blazer and tie brigade frowned upon such behaviour as 'insubordination'.
An incident in the 1970 League Cup final against Celtic, which Rangers won 1-0 is one example where he sat on the ball as play raged on. As he told the Scotsman last year:
“The famous one was the 1970 League Cup final. I did it towards the end but honestly not to antagonise.
"Jim Craig was backing off me and also I was bloody knackered. I turned round to see Jinky (Jimmy Johnstone) turn purple, the veins in his neck throbbing.
“Later, (Willie) Waddell (who had replaced Symon as manager) wanted to see me. I’m thinking: ‘What did I do wrong? I just had a wee drink with Margaret (Willie's wife) to celebrate, that was all’.
"I waited for the green light. On the boss’s desk there was this mountain of letters.
"I didn’t think he was there until he popped up his head. ‘This is not flippin’ fanmail’, he said.
"I had to apologise to Celtic and was fined a week’s wages which he said he’d give me back if I was good for the rest of the season. I never saw that 60 quid again.”
In an exhibition match in New York a few months later against Italian side Fiorentina, Johnston was sent off for retaliating to a marker leaving a set of studs in his leg.
He refused to leave the pitch and vociferously protested his innocence.
The principled stand came to an end when a New York cop was said to have strode onto the pitch with a firearm pointed at Johnston demanding that he 'get off the pitch now'. He walked.
It wasn't all japes and red cards though. Johnston's finest hour for Rangers came in the 1972 European Cup-winners Cup final when he grabbed two goals in the 3-2 win against Dynamo Moscow.
However, unlike the European triumphs of Celtic and Aberdeen, photos of the cup presentation are scarce - it was given to captain John Greig in a room no bigger than a closet due to a riot taking place on the pitch between Rangers fans and the Barcelona constabulary.
The following season saw Johnston banned by the SFA for 63 days after a dust-up with a Partick Thistle player - it was the usual story. Hacked by marker, whacks marker back, early bath and SFA sanction.
By then he was being advised by Billy Bremner of Scotland and Leeds to try out his luck in English football.
It would be a new challenge - not to mention the money being better than it was up north.
He signed for West Bromwich Albion for £138,000 - a record back then for a player transferred from a Scottish club to an English one.
It started off fine but then he found that there were as many hackers in England as there were back home (the likes of Alf Ramsay and Don Revie continually turned blind eyes to such discrepancies - the former would even be hypocritical enough to accuse opposing sides of being 'dirty').
As Johnston said in the Sunday Herald back in 2009:
"It was a lot easier in England than it was up here. At that time, they’d never heard of wingers. Alf Ramsey had got rid of them all. So the full-backs didn’t know how to play me. It was easy at first, a doddle.
"But then… Tommy Smith, he was fair; Norman Hunter too; the dirty merchants were Gilesey (Johnny Giles), (Billy) Bremner, Allan Clarke; then you had Terry Paine from Southampton; he was a winger but an assassin.
“Big Jim Holton done me; six weeks he put me out. He nailed me a cracker. Frank Lampard (Snr) broke my leg at West Ham. I got him back. I did. F*****g into the hospital. I had to wait for about a season. I got Holton back at Old Trafford; he knew he was getting it, anyway.
“You see, I was an eye for an eye man. If you done me, I was coming back to get you. If you laid down, you had no chance. They would have just run over the top of you. They would look for you in that tunnel.
"London was the worst. If you were playing Chelsea, Tottenham or even Arsenal, you’d hear someone saying: ‘Where’s this c*** Johnston?’ I used to stand there and shout back: ‘I’ll be there the noo'. Go f****** high’ they’d whisper. That was the thing at that time. I’d say: ‘You’re gaun high…well, I’m gaun higher! Go f****** high!’ That was me. I didnae give a f***!”
His manager at West Brom when he arrived was Don Howe who had assisted Bertie Mee into guiding Arsenal to the double in 1971.
However, as he told the Birmingham Mail in 2013, he and Howe didn't exactly hit it off:
"Don Howe came to Ibrox and was walking up the marble staircase – I was walking down the steps from the manager’s office,” recalled Johnston.
"He walked past and didn’t recognise me. Don didn’t want me – it was Jim Gaunt, the chairman, who wanted me. He wanted a winger.
"So I came to England and ended up being the best left-back in the league because I was playing so far down the park.
"Jim ended up coming into the dressing room and told Don ‘you’ve got one of the best wingers in Europe... and you’re playing him at left back?’ That was Don – he liked his clean sheets.
"I got on with Don but it got to the stage that if we got beaten I’d get the blame. I’d hold my arms out and say ‘go on, put the nails in’.
"Don’t get me wrong, he was a great coach but man-management was poor. He didn’t know what to do, or what to say."
West Brom were evolving into a very attractive team to watch with Johnston's own flair being complement by the emerging talent of Laurie Cunningham, Brendon Batson and Cyrille Regis.
Of the trio, he told the Birmingham Mail in the same interview above:
"Aye...they were brilliant. Brendon was a good defender. He played at right-back but he could play as sweeper or centre half.
"Laurie was special. He would glide along the pitch. He played in my position and made it look so easy.
"Cyrille was another one - he should have got more caps for England. I always used to jokingly say to him ‘come and play for Scotland’."
"The purchase of a greenhouse is my top story. I’m about to take a corner and waiting for the cavalry to arrive.
"This boy, who sat near the corner flag every week, says: ‘Willie, they tell me you’re a good gardener but that you haven’t got a greenhouse. I’ve got one for sale'.
"My manager, Johnny Giles, is going crazy, wanting me to get the ball over. I’m shouting at him that I’m waiting on big John Wile coming up.
"Anyway, the next time there’s a corner, I says to this fan: ‘How much do you want?’ He disnae miss a beat. ‘Eighty quid,’ he says. ‘Away and take a f*** tae yerself!’ I says. ‘I could get a new one for that.’
"Another corner later, I think I eventually got him down to about forty or fifty quid. I got it delivered too. I got a right bargain.
"Whenever I was taking a corner at the Hawthorns after that, I used to shake his hand. That’s how serious I was.
"They (managers) would always say: ‘Concentrate for 90 minutes, but I couldn't concentrate for 90 minutes. I’d be bored stiff at outside left. I wanted to play inside."
Although manager Willie Ormond had to fight to get him back in saying to Johnston:
"You’re in my team because you’re the best winger in Britain. But lots of people aren’t happy I’ve brought you back – don’t let me down."
But what should have been the high point of his career turned into one that would mark it for life.
Scotland had been beaten 3-1 by Peru.
Despite starting well, they struggled to match the tempo lifted by the South Americans who ran out comfortable winners.
No one really comes off that pitch in a dark blue shirt with much credit - first half-hour aside, Scotland were awful.
Kenny Dalglish and Archie Gemmill are selected at random by Fifa observers for a drugs test.
Gemmill, however, cannot provide a urine sample due to dehydration.
Another player is required.
A hand goes up to volunteer.
It is Johnston's.
As he told the Herald in 2003:
'"I knew nothing about anything. I always had hay fever and my doctor had told me to take these Reactivan tablets.
"So before the Peru match, which you'll know we lost, sadly, 3-1, I popped two of them in my mouth. '
"After the match they're wanting a urine test, aren't they, and I think Archie Gemmill was meant to do it. For some reason Archie wasn't up to it so I said: 'I'll go.'
"The next thing I know, we're at that reception for Scotland players and officials that night, when Trevor McDonald and the ITV crew suddenly come upon me and switch on their lights. I'm thinking: 'What the f***'s all this about?'
'"I genuinely didn't know what was going on. But Asa Hartford suddenly yanked me and said: 'Hey, wee man, you've failed the test!'
"Well, that was it. Ernie Walker (SFA President) ordered me to my room, and the next day, like a criminal, I was driven away beneath a blanket to Buenos Aires airport and put on a 29-hour journey home."
McLeod on hearing this and seeing the respective bottles orders them to be flung out of the hotel window.
The next morning, it is reported that the cows grazing in the field next to Scotland's hotel in Argentina seem to be jumping around with more vigour than is normal for that type of beast.
Seems they had more than just a bowl of cornflakes for breakfast.
There is also a theory doing the rounds which gains credence in later years.
Host nation Argentina, although under a violently anti-communist regime, had been taking notes at how the ultra-left dictatorships in Eastern Europe were cleaning up in the Olympic games - especially in running, lifting and swimming events.
East Germany in particular had been popping pills and injecting fluids like no tomorrow - and it seemed to be working.
It was alleged many years later that Argentina were prepared to go to the same lengths - one unnamed player was said to have a positive test hushed up (the urine sample had him down as being 'pregnant').
The theory goes that a patsy was needed - preferably from one of the smaller nations - in order to deflect attention from what may have been going on with the hosts.
Was Johnston the fall guy?
A year earlier, Scotland had toured South America. During a 1-1 draw with Argentina, Johnston had run right-back Vicente Pernia ragged.
Frustrated, the Argentinian spat in his face and knocked him down with a punch to the kidneys.
Pernia was sent off. Bizarrely, so too was Johnston who for once hadn't thrown a retaliatory swipe back.
Afterwards, the players are socialising at a bar and Argentina's Leopoldo Luque approaches Johnston and, according to Willie in his book - "Sent Off At Gunpoint" - says:
"John-ston ... you good player. But do not come back to Argentina"
Thirty years later, he finds out that the situation could have been much worse for him.
Government files for a particular year are released out into the open three decades later and back in 2008, the file for 1978 made for interesting reading.
The British charge d'affaires in Buenos Aires, Hugh Carless, had written to the Foreign Office in London saying how wise it was that the SFA bundled Johnston into a plane back to the UK in double-quick time.
As the Daily Record stated in 2008, Carless wrote:
"An Argentine lawyer has demanded Johnston's extradition on the grounds that the use of drugs by sportsmen to boost performance is a crime punishable by imprisonment of between one and three years.
"Both Fifa and the Argentine ministry of foreign affairs claim that they have no grounds for interfering with the due process of law.
"They have, however, agreed to seek legal advice on whether a case such as this falls within the competence of the Anglo-Argentine extradition treaty."
In 1980, he gets a phonecall from Rangers manager John Greig asking if he would like to come back to Ibrox.
Johnston later admits he should have turned him down and taken up an offer from Raith Rovers in his native Fife instead - but he agrees to do so.
His eight years away from Scottish club football have broadened the mind and now has him seeing old traditions held by his old club as being somewhat antiquated.
Greig tells him he's on the lookout for a new centre-forward and asks Willie if he can recommend anybody?
Without hesitation, Johnston puts forward Cyrille Regis' name.
As he told the Birmingham Mail in 2013, there were a couple of 'issues':
"I told him to go for Cyrille and it was clear that the fact he was black might be an issue for Rangers.
"These were different times. I just said ‘dye his hair red’, if that helps.
"The next question John asked was ‘is he Catholic?’ I had no idea whether he was. (NB. Cyrille Regis was raised as a Catholic by his French Guianese parents)
"Again, I said ‘he’ll be a Protestant if you want him to be’. But that was a big thing back then.
"I said Cyrille would be the first player I would sign if I was Rangers manager - but it didn’t happen."
All it seems to be remembered for is a vicious stamp on Aberdeen's John McMaster which left the Dons player needing to receive the kiss of life on the pitch.
The pathetic excuse of "I thought it was Willie Miller" does him little favour. However, years later he admits to not being too proud of that affair and regrets doing it.
His career looks to be over until one day he receives an SOS call from Edinburgh.
Former Rangers team-mate Alex MacDonald has become manager of Hearts.
He has persuaded another friend of his and Willie's, Sandy Jardine, to be a player-assistant manager.
Jimmy Bone, who has had a varied career up and down the country signs up as well.
MacDonald wants Johnston to come along and add his experience for the crop of promising youngsters - such as John Robertson, Gary Mackay and Dave Bowman - he needs to whip into shape in order to win promotion into the top-flight.
He agrees - although being called 'Granddad' by one of the impertinent young pups isn't exactly an endearing start.
Eventually though, the boys get the message that they can learn something from the old hands their gaffer has brought in - Johnston especially.
He would regularly hold court in a boot cupboard which he had turned into his own private smoking room.
The young players would file in and listen attentively. As Gary Mackay says:
"Willie Johnston is one of the nicest gents I have ever met. If you wanted someone to look after you, someone to sit you down and talk you through the pitfalls of the game, he time in abundance for everybody to do just that.
"I have a lot of respect for guys that I played alongside but out of everybody, and I mean everybody, Willie Johnston is the one I had most respect for.
"He had a wee room to himself and he'd go in there before training for his fags and his cup of tea. When I could see him through the smoke clouds, we used to chat away and I learned a lot in that room. Even though my lungs suffered like Hell.
"He taught all of us young players at Hearts to play on the edge and with no fear. Having this older guy ask for the ball in games when we had our backs to the wall was a huge lesson and taught me never to hide during games."
A Scottish Cup tie against Celtic at Parkhead in 1983 saw Johnston get ready to take a throw-in.
Celtic's Davie Provan - for reasons known only to himself - goes up to Johnston inches from his faces.
Verbals are shouted and then Provan is on the deck writhing around in agony as if whacked by Ernie Shavers himself.
The referee sends off Johnston who is furious and has to be dragged off the pitch by MacDonald and Jardine.
He is adamant that he never touched Provan. Hearts owner Wallace Mercer believes him and lodges a protest to the SFA.
Mercer then threatens legal action when it emerges that two policemen patrolling the touchline say that Johnston never laid a finger on Provan.
He is only suspended for one game - still a punishment but one that could have been worse had Mercer not intervened. Provan is let off.
Johnston though can't let it lie and in his autobiography released later that year ("On The Wing" which he would 25 years later denounce as being "a load of s****" - probably to promote the second autobiography he was about to release), he rails in very strong terms against Provan's 'cheating'.
The SFA want a word. As Johnston would tell the Sunday Herald in 2009:
"I just went in, sat down, and this boy from Forfar, Brechin or wherever tells me that I’m a disgrace to football and a disgrace to this nation.
"I didn't even know him. I says: 'Tell me your f****** name.’ And Ernie Walker, the chairman, says: ‘Willie, don’t start.’
"I says: ‘He’s f****** started.’ And I says to the boy himself: ‘I’ve done more for Scottish football than you’ll ever do in your whole entire life … you w*****'.
"At the end, Walker asks me if I had anything to say. ‘Yeah,’ I replied, ‘it’s now f****** half past one and you’re all going for your lunch. You’ve fined me £200. The wine’s on me.’”
He was instrumental in helping the club win promotion to the Premier League in 1983 and in the following season, helped them qualify for Europe.
Lest we forget that the likes of Mackay and Robertson benefited greatly from his tutelage given the long and honourable service they put in for Hearts long after Johnston had left the club.
His career dwindled to a close soon after and chose the path that many ex-players take, if management or coaching is not their scene, by running his own pub.
Despite his efforts on the pitch, he would still be remembered for one failed urine test in Argentina.
Whenever a drugs in sport story cropped up, it would be a given that a reporter would give the Port Brae bar in Kirkcaldy a call - and usually got a terse response back.
We'll leave with the man himself telling the Birmingham Mail back in 2013 of one such bizarre phonecall:
"In the 1988 Olympics the Canadian sprinter Ben Johnson was stripped of his gold medal for taking drugs and I had a call from the Sun newspaper.
"I kid you not, he said to me 'Willie, can you confirm that you're related to Ben Johnson? Is he your brother?' I replied 'well my father stayed in Canada when I was playing there so....'
"Seriously, what do you say to that kind of question? That's what it was like for a long time. Whenever someone got caught taking drugs my phone wouldn't stop ringing. Welcome to my life."