Everyone knows the impact that Johan Cruyff had footballing philosophy of Barcelona. But what if there had been another totemic figure present at the Camp Nou? What if El Tel had decided to depart a season early? Alex Dimond, ladies and gentlemen.

These days, Terry Venables’ impact on the pop charts might actually be slightly greater than his impact on elite-level football.

A prized pundit for The Sun — who seem to ask him to cover old Elvis Presley songs for advertising purposes (‘If I Can Dream’ – No.23 earlier this year) as often as they ask for his insight into the beautiful game — Venables has long since left the dugout he once patrolled so proudly, and at least proficiently enough to be named manager of his country for a memorable, albeit short, spell.

That isn’t to say the now 67-year-old hasn’t left any sort of legacy to the game he left school as a 15-year-old to pursue as his life’s work. After all, how could that be the case for a player who was the first to represent the national team at every level during a respectable playing career, before embarking on a managerial career that brought similar recognition?

Interestingly, however, it is arguably the impact of one, seemingly minor, decision he made in the summer of 1986 that still holds the greatest repercussions for two of biggest clubs, and most successful dynasties, in the history of the game.

That decision — to stay on as the manager of Barcelona — was greeted at the time with minimal fuss; acceptance but not elation on the part of the club’s board. Off the back of an ultimately disappointing campaign, the man affectionately known around the Nou Camp as ‘Meester’ (having initially been forced to overcome jibes of being an ‘English tourist’) had earlier intimated to the board that he was likely to stand down.

A Copa del Rey trophy to show for the campaign’s endeavours had been a disappointment, especially in light of the Primera Division triumph of Venables’ first year — though both were undoubtedly overshadowed by the regret and recrimination that had followed the club’s European Cup final failure.

It was this failure that had Venables considering a departure, as Barca lost out on a long-awaited first European crown on penalties to Steaua Bucharest, in what was effectively a home final in Seville — a fact only made worse as his side missed every one of their attempts in the shootout.

Successors were lined up, interviews arranged. And then Venables changed his mind, and any plans that had been made were quickly shelved.

Nothing would be won in the 1986-87 season, as Real Madrid strengthened their grip on the domestic scene, and, after a poor start to the 1987/88 season, ‘El Tel’ (as he would continue to be known in his home country) was fired. In his place stepped up Luis Aragonés, who had made a name for himself with Atletico Madrid.

But what if Venables had stuck with his initial intention to leave during that summer at Camp Nou? Who would have replaced him then?

Howard Kendall, of Everton, was one candidate considered (this being an era when British managers were not the laughing stock of Europe), while Bobby Robson, who had his hands full with the English national team post but was nevertheless a highly-regarded confidant and advisor of the club’s hierarchy (he recommended Venables to them in the first place), was also sounded out. But the front-runner was an up-and-coming young manager from successful Aberdeen, who had successfully broken up the Old Firm duopoly and, only three years prior, masterminded a memorable Cup Winners’ Cup victory over Barça's arch-rivals Real Madrid — Alex Ferguson.

"I had plenty of offers,” the Scot, Manchester United manager for the last 24 years, reflected recently. “When I was at Aberdeen, I was interviewed for the Barcelona job. It would have been 1985 [a rare lapse in memory from Ferguson], Terry Venables, who was then their manager, recommended me and we met at the Connaught Hotel [in London].

“But Terry stayed on another year.”

And that was that. Little over four months later, in November of 86, Ferguson was being unveiled at Old Trafford, a position that he has held ever since while winning every trophy going. For those who played for the fiery Scot at Pittodrie, his destination was little surprise.

“He said he would leave Aberdeen for one of only two clubs – Barcelona or Manchester United,” Gordon Strachan, a diminutive winger who made his name under the Scot at Pittodrie, later noted.

"That would have been a challenge, managing Barcelona, adapting to a different lifestyle and learning a different language,” Ferguson agreed. ”There were other offers too [he turned down strong overtures from Wolves, Spurs and Arsenal in the weeks and months prior to his United switch].

“But once you're ensconced here at United, it becomes really hard to leave. You sort of get engrained into the place and the harder it gets to even contemplate retiring or think about the day you won't be here.”

Ferguson has gone on to win 11 Premier League titles at Old Trafford, along with two Champions League crowns and many domestic and inter-continental trophies, a collection that has firmly established him as one of the greatest managers in the history of the game. But the early years after his move south of the border were not the smoothest, and only an FA Cup victory (after a replay) against Crystal Palace in 1990 finally gave him the room to eventually build his dynasty.

Even that watershed moment only came after a famous Mark Robins strike against Nottingham Forest that many still believe saved the manager from the sack.

Barcelona, in that same four year period since Venables’ decision, underwent similar turmoil. The Englishman lasted until late in 1987, where he was replaced by Aragonés — a temporary solution to some fairly permanent cracks within the club’s structure. The Spaniard, who would later lead the national team to European Championship success in 2008, inadvertently only confirmed the fleeting nature of his tenure by backing the players in their uprising (known as the Hesperia mutiny) against the club’s controversial chairman, Josep Lluís Núñez, at the end of the 1987-88 season.

That paved the way for the club’s former star, Johan Cruyff — a titan of the game as both player and philosopher — to join the club once again from Ajax and rebuild the playing side of the club (Núñez had fired every player involved with the mutiny, bar Andoni Zubizarreta). His tenure would not be as long as Ferguson’s at United (he would be another to fall out with the irascible Núñez), but its impact was just as significant.

The Dutchman imprinted his own footballing ideology on the club — most notably the forerunner of the 4-3-3 system the side still employs today — and overhauled the club’s approach to the game. La Masia, an innocuous former farm converted by Núñez and the club at the start of the decade to house foreign trainees, became a more focused source of players from all backgrounds and carefully chartered production line that led directly to the first team.

One of the first to benefit was a young Josep 'Pep' Guardiola. After pitching up to watch the youth team in his first week in the job, Cruyff pulled the youth team coach at the time, Charly Rexach, to one side and instructed him to move the skinny lad on the right side of midfield into the centre, to act as the pivot. That young boy was Guardiola, and within in two years, still only 19, he would fulfill that role in what would become Cruyff’s ‘Dream Team’.

That ‘Dream Team’ would win that elusive first European Cup crown in 1992, a landmark achievement for the club at the time. But only a year prior they had faced off against Man United and Ferguson, in the final of the Cup Winners’ Cup. Perhaps underlining the fact United were a couple of years further down the line in their revolution (Cruyff was still preserving with his idealistic 3-1-4-2 formation, but by the next year would have moved to the now-iconic 4-3-3), the English side emerged victorious thanks to two goals from Mark Hughes, himself a former Barca forward under Venables (Hughes, signed along with Gary Lineker by Venables after he decided to stay in Spain, scored past goalkeeper Carlos Busquets, the father of Sergio — a midfielder who would play a role in one of Barca’s revenge victories 17 years later).

Sir Alex had won his first European trophy, against the club that nearly employed him.

The paths of the two would continue to cross at pertinent moments. Eight years later, Ferguson would win the Champions League at Barcelona’s home ground in a last-gasp win against Bayern Munich. Ten years after that, Barça would beat United as Fergie and his club searched for a second successive European crown.

The Barça manager that day? Pep Guardiola, of course.

“Cruyff and Rexach were the first to get that way of playing started,” the dapper successor to his mentor’s ideals said after perhaps his most famous victory to date; a 5-0 drubbing of Madrid at the end of 2010.

“That’s the track to take and those of us who have come after them must be loyal to that. It’s an idea that we shouldn’t betray – it has been implanted in this club for a long time now.”

Such incidences and statements only illustrate the widespread impact of Cruyff’s tenure, and thus, by association, Venables’ decision. Would Guardiola have been able to embark on the same sort of career at the club, first as a player and then as a manager, had Cruyff not come at the opportune time he did and change the outlook of both one academy trainee and the club as a whole?

Ferguson already held a healthy awareness of the potential value of a club’s youth system (the production line at St Mirren, his second club, was in many ways his calling card), so it is likely Guardiola and La Masia would still have been utilized under Ferguson. But would Guardiola have had his position changed to such effect, especially as Ferguson has always been more of an exponent of variations on a 4-4-2, rather than a formation that requires an anchor (Roy Keane, arguably Guardiola’s nearest relative in United’s side, was a very different type of driving force)?

The knock-on effect of Venables’ decision arguably spreads even further. With Cruyff in situ until his fallout with Núñez in 1996, confidant Robson had six years to fill between his departure from England in 1990 and his final, inevitable (albeit temporary) appointment at Camp Nou. After two successful years with PSV Eindhoven, the other four were spent in Portugal (first with Sporting Lisbon, then FC Porto) — where the future knight of the realm picked up a certain ambitious youngster called José Mourinho to act as his translator and aide.

Mourinho, bereft of a stellar resume as a player but possessing of great tactical ideas about the game, learned from Robson and followed him to Barcelona, where he would also study under Robson’s successor, Louis van Gaal (who let him oversee Barcelona B) before moving back to his homeland and embarking on his own managerial career.

After a tumultuous beginning at Benfica and a record 5^th place finish with União de Leiria, winning the UEFA Cup and Champions League title at Porto in successive seasons catapulted Mourinho into the big time. The rest is history. But would he have been able to create such an opportunity for himself without Robson’s opportune arrival at Estádio José Alvalade?

Mourinho, as if it needs to be said, is now manager at Real Madrid, widely respected as one of the game’s great modern managers. With Ferguson still at United and Guardiola leading Barcelona to ever greater heights, it is arguable the effects of Venables’ decision in the summer of 1985 can still be seen at the three biggest clubs in the world.

Such an argument is all speculation, of course. Cruyff and Robson always had close links to the Catalan club, and were always likely to be invited to manage it at some point, irrespective of Venables’ whims or Ferguson’s potential success (the rocky start to life at United, coupled with his family’s desire to stay near Scotland and the notorious difficulty and lack of longevity of managing in a foreign country, suggest the Scot would have done well to last more than a few seasons in Spain). The only difference might have been whether their paths would have crossed with Guardiola and Mourinho as they eventually did.

More interestingly, perhaps, is this — when United were searching for a manager to replaced Ron Atkinson in 1986, their search came down to two men; the eventual winner, Ferguson, and a certain ‘Meester’.

"In the boardroom there was a strong feeling for Venables,” Sir Bobby Charlton, a club legend whose influence has naturally eroded over time as Ferguson’s as grown, recalled of the decision-making process.

“I said I understood it well enough. Terry was a marvellous coach who as a player had represented his country at every level. He was another football man of high profile who commanded attention and the respect of his players. Some of our directors emphasised Venables' confidence, his easy manner in front of the television cameras.

"I conceded all of that but then I made the case for Alex Ferguson. I pointed out the unique scale of his achievement in Scotland; no club could seriously consider taking on the Glasgow powers but that was the mission Ferguson had declared on his first day at Aberdeen.

“Aberdeen were not supposed to beat Real Madrid in the final of the Cup Winners' Cup [in 1983]. I asked my fellow directors if they had seen Ferguson on the touchline when Aberdeen scored their victory in Gothenburg. I said he had lived passionately every moment of the game, charging on to the pitch, filling his players with self-belief.”

Had Venables been freely available — especially had Ferguson succeeded him in La Liga — then the board might well have won out against Charlton’s persuasive arguments. Considering El Tel’s controversial ventures in football management and directorship in subsequent years (especially considering United had their own ill-advised dalliances with the likes of Michael Knighton as the club looked for a buyer) then it is hard to imagine Venables would have provided the same long-term stabilizing and revolutionary presence Ferguson offered.

United, then, perhaps would have lost most had Venables walked away from Barcelona in ‘86. So too would the Premier League — without Ferguson, United, Cantona and Fergie’s Fledglings, who knows if the Premier League would have taken off as it subsequently did.

Few men can wake a sleeping giant. It took Ferguson a number of years, but eventually he did it. His hiring was a moment of inspiration from Charlton and the board that the club has revelled in ever since.

But for the opportunity to do so, perhaps they — along with Barcelona, Guardiola and Mourinho — owe a debt of thanks, no matter how small, to a 42-year-old Venables and his desire to enjoy the Spanish sun for at least another year.

Not that the man re-born as something of a crooner is looking for such recognition:

“Winning La Liga for Barcelona is the pinnacle of my career in club management,” is his satisfied verdict on that period of his career.

“It was an incredible time there and I loved every minute.”

You can follow Alex on Twitter @alexdimond.