At 57, O'Neill probably has one more big posting in him. The fans of Aston Villa, who have not always been kind to him, are increasingly accepting of the idea that he might find career fulfilment at Villa Park. This is the stated aim. Villa's last trophy came 14 years ago. A decade has passed since they last contested a final, the FA Cup in 2000. Two League Cups is the sum of their labours in the 28 years since Peter Withe bundled the ball off a post in Rotterdam to win the European Cup.
O'Neill tells you that this is his focus, that the biggest job in domestic football is not a matter for him. "I have never thought about that at all, not for one second, not even when I was up at Celtic. Sir Alex Ferguson will decide, I would reckon probably in the year 2033, when he feels the Champions League has passed him by one last time. I will have departed this earth long before him."
O'Neill distances himself from the pageant with characteristic charm. The glow of FA Cup victory over Crystal Palace the night before is still on him. The Pullman that will take the team to London is parked at the door. A sense of anticipation is building. O'Neill is at the centre of the narrative. You sense he would be happy to talk all day. On another afternoon the question of the Ferguson succession might send him spinning out of Bodymoor Heath in a haze of expletives. On this day, he is happy to play keepie uppie with the theme.
"Following Ferguson is the impossible job, absolutely. How many times as he won the championship? Ten times, something like that? It has never really bothered me. There is always somebody coming up, somebody whose name is relevant at the time. I never pay any attention to it. I really enjoy my job here. For us to win a couple of competitions in the next couple of seasons is what it is all about, to qualify for the Champions League, that sort of stuff."
O'Neill takes questions like Socrates at the Acropolis, stroking his chin in contemplation, as if teasing the words from his mouth in precise order. "The fact that I'm facing Sir Alex Ferguson does not make the difference. The fact that we are in a final at Wembley is enough for you to want to do your very best, to show off your ability. When you are up against Manchester United and Sir Alex in the final it is not so much that you want to raise your game, you have to if you are to win."
Oh come now Martin, you have taken four points off him already this season, three of those at Old Trafford. What's to fear? Surely you have his measure. The thought prompts another caress of the jaw, and a smile that suggests the Priory is the place for any who believe that. "I don't think that for one second. People have been trying for a lot of years to get the measure of him. He has done an amazing job even to be at Old Trafford as long as he has, at a club that is demanding success. He has delivered and continues to deliver."
OK, that's enough about Ferguson. O'Neill is unique in the upper echelon of English football in his adherence to a domestic template. This is not about believing absolutely in English virtues but in following a line of thinking that respects the league in which he works. Were he in Italy the core would be Italian, German in Germany and so on. That his captain today, Stiliyan Petrov, is Bulgarian, does not contradict the broad sweep of O'Neill's rationale. Neither does the inclusion of John Carew or Carlos Cuéllar. The thrust of the Villa proposition is carried by James Milner, Ashley Young, Gabriel Agbonlahor, Stewart Downing, Emile Heskey, Stephen Warnock, Luke Young and so on.
"I do feel that the heartbeat of the football club should be (the nationality of) the league that you are playing in, the core of this team is fundamentally English. That does not mean that I hold everything by it. At Celtic I had a group of Swedes that loved it to death."
O'Neill is half way through his fourth year at Villa Park. According to some his reliance on a traditional English structure does not stop at birth certificates. After their recent meeting Arsenal aesthete Arsène Wenger reached for the long ball stick with which to beat O'Neill. Wenger rarely sees virtues in the opposition when they get the better of his team. His stylistic hauteur gets right up O'Neill's nose. Perceptions, one might say, have yet to catch up with the evolving brand of adventure O'Neill is orchestrating.
"The stats showed that we played three more long balls than they (Arsenal) did in the game. I had a wee smile when Bacari Sagna hoofed it 80 yards up the pitch in the first few minutes against Sunderland. I get irritated. I should have remembered that he said Manchester United were anti-football."
Victory today, O'Neill believes, will authenticate his approach and reinforce in the Villa players a greater sense of their own worth. It will also keep the debate rattling along, ensuring that when Fergie retires to the turf, Jose Mourinho will not have it all his own way.