If there was an echo of time gone by at Celtic Park this season as Neil Lennon returned from the winter break to go into games with two strikers up front and a back three, it is not the only thing that still resonates from Martin O’Neill’s Celtic era.

It is 20 years today since O’Neill stood on the steps at Celtic Park and promised to “do everything I can to bring some success to this football club.” If his words was understated, his impact was not. O’Neill inherited a squad devoid of leadership and rife with division and immediately impressed upon it his own way of working.

That first season saw a 36-point swing as a team who had lost the league by 21 points performed a clean domestic sweep. It was Celtic’s first Treble since 1969.

By the time he left in 2005, he had won three titles, three Scottish Cups and a League Cup, been to a UEFA Cup final and remoulded Celtic’s European reputation in participation in the Champions League – but the power shift that took place in that seismic first season has never been diluted.

“I think we lit the fuse,” said O’Neill. “The place was just waiting for an enormous lift. Where Celtic were back then is exactly where Rangers are now and you know how must demoralising it must be. You are sitting back and watching your rivals take over everything, you are playing second fiddle and it settles on you as a club. It settles into everything. You wonder when you are ever getting out of the mess.

“Celtic were in the doldrums and I think we lifted it. Without wanting to be too immodest, I do think some of the dominance now stems from that and the change in mentality around the club.

“I remember talking to the Lisbon Lions and getting to know them when I was just getting my feet under the desk. I always remember their message being that as a Celtic fan they would have a little bit of hope for a month or two and then it quickly dissipated. I do believe that at the start of the century and that way that we broke Rangers’ stranglehold on the domestic landscape would have been significant in what has stemmed from that today.

“Fergus McCann deserves an awful lot of credit. He put the infrastructure there that was fit and proper for a modern football club. Celtic deserved that. They deserved that big monolithic stadium. But at Celtic it is always got to be more about just enjoying your football. It has to be more than just looking good and looking the part – you have got to win.

“If I remember correctly that season when I first arrived Dick Advocaat signed a whole load of players. He said that he wanted one team for the league and one team for the Champions League. Well, you hear that kind of thing and you know, you’re thinking well, that might come back to bite at some point.

“Rangers were going into the Champions League and we were having to play a qualifier against Jeunesse Esch just to get into Europe. But realistically, that was where we were as a club.”

In the two decades that have elapsed since O’Neill’s arrival at Celtic, the Parkhead side have lost five titles. Four of which have been lost on the final day of the season and only one was lost by any significant margin; Rangers won the championship in 2011 with a six-point lead.

Prior to O’Neill’s arrival Celtic had won just three titles in 18 years. But of the seven trophies that O’Neill won during his time in Glasgow, the one that got away still pains him. If Helicopter Sunday was a sore one to take and the loss of the 2003 title at Rugby Park that was lost on goal difference felt like a punch in the guts, time has never assuaged the pain of the UEFA Cup final against Jose Mourinho’s Porto.

“I look back and I honestly still think that the team we built should have win the UEFA Cup against a Porto side who would go on and win the Champions League the next season,” said the 68-year-old. “I do think that team was the forerunner for what is happening at Celtic now, albeit I know that Rangers have had so many financial problems.

“I think we would all say that the best and most celebrated team Celtic have ever had is Jock Stein’s ’67 team. It would be impossible to emulate that European Cup win and the glorious achievements they enjoyed. I’ll confess to not knowing too much what Celtic would have looked like in the ‘30s or the ‘50s and whatnot but I don’t think since 1967 there was a better Celtic than the one from our era.

“We had young guys like Stiliyan Petrov who was energetic and hungry, we had the real finesse of Henrik Larsson and the intelligence of Chris Sutton. We had real fire power done the flanks with Didier Agathe and Alan Thompson, we had the power of big Bobo Balde in defence.

“The balance of that team was great but it was the way they gelled together which made them a very good football team. And what I think is frequently overlooked is that when it came to European football, they were all relative novices. We were playing in the Champions League against Juventus and Bayern Munich and never once did we think that we couldn’t compete. And whatever they might have stood accused of in terms of deficiencies, there would be no-one who could have faulted a lack of spirit or endeavour.”