This weekend, Celtic will begin their defence of the Scottish Premiership with a trip to Hearts. Now under the stewardship of Brendan Rogers, the Glasgow giants will be hunting a sixth successive domestic title, while the return of Old Firm rivals Rangers should serve to revitalise outside interest in what had become an increasingly insular domestic competition. For the first time in years, there is a buzz about the Scottish game.
Six titles on the spin would be an impressive achievement, though the absence of their intra-city opponents and only serious competitors over the past four years does somewhat take the shine off it.
Besides, they've won more successive championships in the past, and done so against stronger opposition. From 1965 through 1974, Celtic were the unquestioned kings of the Scottish game, racking up nine titles without reply – as well as a European Cup and numerous other domestic honours.
They were led for the entirety of this period by Jock Stein, whose success in the Parkhead dugout has made him synonymous with Celtic Football Club. Indeed, Stein helped to shape the image of the all-powerful, no-nonsense Scottish football manager. His blueprint was adopted by many – not least Alex Ferguson.
And yet, the man himself did not expect to be handed the keys to the manager's office. A former coalminer who began his professional career at Welsh side Llanelli Town, Stein made more than 100 appearances for Celtic as a player. He later managed their reserve side, but believed he was unlikely to be given the top job due to his Protestant faith. Celtic, of course, have always been inextricably linked with Catholicism.
After leaving his Celtic reserves role Stein managed Dunfermline and Hibernian, leading the former to the Scottish Cup in 1961 and steering the latter towards the top of the Scottish table. This was enough to convince Celtic that he should be their new boss for the 1965/66 season, with Stein eventually agreeing to take over early. He took up the reigns in March 1965, giving him a head-start on turning Celtic into a title-winning machine. Stein thus became the club's first Protestant boss – and only their fourth of any stripe since being formed in 1887.
Though he could not do much for Celtic's poor league showing – they finished that season eighth, a low that has not been repeated since – Stein did take over a side competing for the Scottish Cup. Having guided them through the semi-finals via a replay against Motherwell, he got an early shot at silverware. Taking on his old side Dunfermline in front of 108,000 fans at Hampden Park, Celtic twice came from behind to lift the cup. It was their first major honour since the Scottish League Cup seven years earlier.
Success breeds success – winning is as much a mental achievement as a physical one – and so it should not be a huge shock that Celtic's fortunes began to lift after this triumph.
But what could not have been predicted is the speed and dominance with which the rejuvenation occurred. In Stein's first full season as boss, Celtic became champions of Scotland for the first time in 12 years. They would not surrender their crown for almost a decade.
There is no doubt that Stein brought something new to the club. Bertie Auld, who played close to 200 games for the Bhoys over two spells, explained as much in an interview with BBC Scotland:
"At most clubs in those days, when you were training you'd run round the track. If you went in at 10 o'clock you were running 'til 12 o'clock," explained Auld.
"Jock didn't see it that way. He thought, if you're a footballer, the most important thing is the ball – it's made round to go round. He introduced the ball to start the training. That was foreign.
"He was so in-depth, thinking about the game. He was well before his time. Everyone was engrossed in what he had to say. It was educational because I'd never experienced that before."
While Stein's fresh and detailed approach undoubtedly contributed significantly, so too did the signing of Joe McBride. As Motherwell's top goal-scorer for three successive seasons, this was not so much a canny transfer as a patently obvious one. Of course, not all obvious transfers pay off – Roman Abramovich is unlikely to consider £50m for a pale impression of Fernando Torres money well spent – but McBride's move to Parkhead certainly did. Signed for £22,000, McBride was the league's joint-top scorer with 31 goals (the other man to net 31 that season was one Alex Ferguson).
It was a vintage season for the Bhoys: they also won the Scottish League Cup, were Scottish Cup runners-up, and reached the semi-finals of the Cup Winners' Cup, losing out to Bill Shankly's Liverpool.
That represented a superb campaign for the club, a return to form that Stein and his side could rightly be proud of. Still, what followed would eclipse it entirely.
Domestically, Celtic cleaned up in 1966/67: they were league champions again, beating Rangers by three points, and lifted the Scottish Cup and League Cup, beating Aberdeen in the former and the Gers in the latter.
Nonetheless, it's their European exploits that season which will forever be remembered, with Stein leading his 'Lions of Lisbon' to a famous European Cup success.
The competition was still in its infancy at the time, and had been won by just four clubs in 11 years: Real Madrid, Benfica, and the two Milan sides, Internazionale and AC Milan.
Celtic succeeded where several top British sides had failed by reaching the final. They were helped by two of the favourites – Real and Inter – facing off in the quarter-finals, with the Italian club prevailing. Celtic beat Yugoslav side FK Vojvodina in the quarters, then avoided the Italians in the last four. The Bhoys faced Dukla Prague, winning the home leg 3-1 and then drawing 0-0 in Czechoslovakia to book their spot in the final.
Inter were undoubtedly heavy favourites to lift the trophy at the Estádio Nacional in Lisbon, having won the past two European Cups and back-to-back Serie A titles. Managed by Helenio Herrera, a key exponent of the catenaccio ("door-bolt") system, they had earned the nickname Grande Inter.
The game looked to be heading in the Italians' favour early on when Celtic right-back Jim Craig gave away a clear penalty. Sandro Mazzola converted it, sending goalkeeper Ronnie Simpson the wrong way, and Inter led 1-0 with six minutes on the clock. But while they withdrew into their defensive shells, Celtic attacked with verve, Inter goalkeeper Giuliano Sarti proving vital to his side's 1-0 half-time lead.
The second half resumed in a similar fashion. But, a little after the hour, Tommy Gemmell finally levelled things up for Celtic. The ball was knocked into his path from the right-hand side of the box. Gemmell charged on to it and fired a powerful shot home. 1-1.
Inter still seemed more content to defend than attack, and with less than 10 minutes to go it cost them dearly. This time it was a long-range shot from right-half Bobby Murdoch, which top-scorer Stevie Chalmers got a foot on to send the ball past a helpless Sarti. Just over five minutes remained and Celtic had enough to hold out. They were champions of Europe.
What made their triumph all the more incredible was the composition of their team, with all but one member of their 15-man squad born within 10 miles of their Celtic Park home. Outside-left Bobby Lennox was a relative foreigner, hailing from 30 miles away in Saltcoats, North Ayrshire. It's no exaggeration to suggest that a repeat of this would be impossible in the modern era.
Celtic had won their domestic title, both cups and the European Cup – this was an unprecedented achievement for Stein and his side, and one that they could hardly hope to repeat. Indeed, Celtic remain the only Scottish side to have lifted the European Cup.
But the success did not stop there. They won the next seven Scottish titles without reply, thus setting a new record of successive championships. Their most dominant campaigns came in 1969/70 – when they finished 12 points clear of Rangers – and 1971/72, when they beat Aberdeen to top spot by 10 points. There were close-run affairs, too: their first three titles were won by two, three and two points respectively, while they pipped Rangers to the 1972/73 crown by a single point.
The closest they would come to repeating the glory of 1967 was in 1970. League winners for the fifth time in a row, they also won the Scottish League Cup and were runners-up in the Scottish Cup.
They reached the European Cup final for a second time, too, beating the mighty Leeds United in the semis (the second leg was played in front of an absurd attendance of 136,505). However they could not repeat the heroics of 1967, losing 2-1 to Feyenoord after conceding deep into extra-time.
Since his death, Stein has been accused of complacency ahead of the 1970 European Cup final.
Celtic were finally toppled as domestic champions in 1974/75 when they slipped to third, 11 points off champions Rangers and four behind Hibernian, thought they did win both cups. Rangers were champions again the following year and Stein's men could not win a cup, meaning he had failed to lead Celtic to a major honour for the first time in his decade at the club. They were back on top the next year, however, beating Rangers to the league by nine points and also lifting the Scottish Cup.
But that would signal the final glory of the Stein-Celtic partnership. The club could not defend their title, finishing a lowly fifth, and again failed to earn any silverware. Stein was persuaded to step down from his position for the 1978/79 campaign.
He could look back on a glittering period, and do so with tremendous pride. During his 12 full seasons at the club Stein won 10 league titles, eight Scottish Cups, six League Cups, and the European Cup. Only Willie Maley led the Bhoys to more domestic titles, though he had an incredible 43 years in which to claim his 16 championships. Stein's 10 from 12 represents an unbelievable rate of success.
He was offered a role working for Celtic's pools company, but turned it down in the belief he had a future in management. Soon after, he was appointed boss of English giants Leeds United, though it would be a short-lived affair: 44 days after taking the role, he resigned to take up the recently vacated job as Scottish national coach.
In almost seven years at the helm he would never truly live up to his towering reputation. Under his stewardship Scotland reached only one major tournament – the 1982 World Cup – and failed to progress beyond the group stage. He died from a heart attack following a World Cup qualifying match against Wales on 10 September 1985. Stein was 62 years old.
Celtic won the league in their first season without Stein, and took five of the 10 titles following his departure. A barren run between 1988 and 1995 saw them fall into a slump that resembled the pre-Stein years, while arch rivals Rangers went on their own run of dominance. In 1998, however, Celtic wrested the title back, capping Rangers' run at nine – and ensuring the Gers could only equal their record, not overhaul it.
They remain one of Scotland's two truly powerful clubs – and Stein's role in this cannot be underestimated. Speaking at a memorial service in 2015, writer and broadcaster Archie Macpherson suggested that Fergus McCann – who saved the club from financial ruin in the 1990s – would not have been inspired to do so without Stein's legacy.
"If Celtic had continued in 1965 being a run-of-the-mill club, winning a cup every so often, winning the league every so often, being subservient to Rangers as they were at that time, would there have been the same appetite [from McCann] to come in and save that club?" Macpherson asked.
"Stein lifted the club almost stratospherically and got them a European trophy. That's why these people realised: 'We can't let this club flounder – a club of that status'. Consequently, Stein built this [Celtic Park and the club as a whole] as well."
His legacy lives on in a generation of managers, too. Stein was hugely influential on Alex Ferguson, who was his assistant when he died in 1985. Ferguson would go on to become the most successful manager in the history of English football and has, in turn, been influential on a subsequent generation of bosses – not least those who played under him during Manchester United's glory years. In a very real sense, Stein's work lives on in 2016.