Just seventy-one days after his last introduction at Celtic, Martin O’Neill finds himself experiencing familiar emotions once more.

He is filled with anticipation about the new challenge he has embraced, tinged with a touch of anxiety over the possibility of not succeeding this time.

On a more personal note, the past two weeks have been a period of deep sorrow and regret for him.

“You know what?” O’Neill mused, “My biggest regret is not visiting John in recent times.”

“I didn’t get to see him. He surely knew I was in the area,” he added.

Martin O’Neill and John Robertson were part of the great Nottingham Forest side that won the European Cup in 1979 and 1980

O’Neill and Robertson during their playing days together at Nottingham Forrest

Robertson and O’Neill would go on to form a partnership in management after they retired

“But the week I planned to visit him, my granddaughter fell ill and was in and out of the hospital for a couple of days. I kept thinking, I’ll make it there. I’ll go see John.”

‘And I didn’t get to see him. And then I got the call on Christmas Day that he had died, and I’m really disappointed with myself that I didn’t see him in the latter stages.

‘There might have been part of me thinking that maybe I didn’t want to see somebody as frail as he was and maybe that’s your last thought of him, rather than the person I’ve known all these years.

‘So, I don’t know. I’m a bit confused in that sense.

‘But, yeah, real loss, honestly. He really was special, you know. Yeah, a special character.’

He was all that. Robertson was an outstanding footballer too, the star turn of Brian Clough’s title winning, two-times European champions.

When the boots were finally on the peg, he made a perfect foil for O’Neill when the latter moved into management.

Loved by all he worked with for his warmth and humility. Respected in equal measure for his deep knowledge of the game he graced.

‘It would have been some months ago,’ O’Neill recalled of what proved to be their final phone call as Robertson battled Parkinson’s disease.

‘So, I spoke to him, well aware, absolutely …

‘John would get embarrassed with the fact that he wasn’t able to speak to you properly. So, he would be there and maybe he didn’t want you to come up and see him in that shape.

‘But, yeah, he was, honestly, a special boy. A special player, you know, of which I was obviously very jealous of him because he got all the accolades. Quite rightly so.’

What would his great pal have made of all of this? Back at the place where they enjoyed such success at the turn of the century just a couple of months on from leaving?

O’Neill wagers there would be a grin on his face as wide as the Clyde.

‘A third time!’ he smiled. ‘He’d have thought that was laughable. He would, honestly. He would have been like: “You’re not wise Martin”.’

There’s a part of O’Neill which concurs with that sentiment.

‘If I had any sense, I would have said – no, I’m not coming back,’ he added.

‘That’s never been my strong point.’

Everyone knows what O’Neill did when he initially answered Dermot Desmond’s call following Brendan Rodgers’ departure in October.

Seven wins from eight rejuvenated Celtic. When Wilfried Nancy won only two from the same number of games, the case to parachute the veteran back in became compelling.

There’s an expectation among supporters that the 73-year-old will simply wave a magic wand again and that his managerial sorcery will save the season. This assumption makes O’Neill decidedly uneasy.

Robertson and O’Neill enjoyed much success at Celtic during the early 2000s

‘You do have to prove yourself again,’ he admitted. ‘In this game, almost every week, you are having to do this. Honestly, you are only as good as your last result. And that’s it.’

He’s lived with this truth since the days when he and Robertson were trying to make their way in management at Wycombe.

‘In many respects, it is what’s kept me going in the game,’ he explained.

‘I would feel under pressure as well if we lost football matches and people’s expectations of you starts to go on the wane. What do you do?

‘But did I want to do this? Yes, I did. People say you want to come back and do great for a club you love, and yes that is part of it. But you also still want to be involved in football. That’s the point. Even at my age.’

He wasn’t concerned about tarnishing his legacy when he returned last year and he’s not losing sleep over it now.

‘I still don’t care about that,’ he insisted. ‘I care about winning the games, because you’re going back in again, you start losing the football match and people say, listen, (you) should have got out the first time and he’s definitely too old.

‘Remember that old song, what was it? Wish You Were Here. Remember the Pink Floyd song?

‘Like two old fish in the swimming pool year after year. Same old fears. I have the same old fears.

‘I am not past the stage of worrying, I never got past that stage. I am anxious about what’s coming ahead…’

This is countered by the fire he still has in the belly.

‘My knee is crocked, I need an operation,’ he said. ‘But I was playing badminton with my six-year-old granddaughter in the summer, out in the field.

‘And she went in crying because I was winning. She was complaining to her mother: “He’s not letting me win”. No! I’m not letting you win. And she’s six. So, she has an inferiority complex now … given to her by me. If you want to play, you have to compete in the game!’

In his short time away, he watched all of Celtic’s matches under Nancy except the second half against Livingston on account of a pre-arranged appointment.

He was invited to work as a pundit at both the League Cup Final and last weekend’s match against Rangers but thought twice.

‘I didn’t think it was appropriate,’ he explained.

‘I’ve seen it before when I was a manager, and there were boys in the stands, managers who were out of a job, staring down. I didn’t like it.’

He felt sympathy for a good man who just seemed stuck in the wrong movie from the outset.

‘If you turned round and said you felt sorry for an outgoing manager people would say “nonsense” but I did,’ said O’Neill.

‘As a person, he was really well-liked. There has not been one bad word said about him and his backroom staff.

‘I just think that whatever it is, you have to win the football games and that is regardless of what system you do or don’t have or want to implement.’

In this maddest of mad seasons, O’Neill’s return is yet another surreal twist.

O’Neill said Robertson would have found him going back to Celtic for a third time ‘laughable’

It’s not just with the benefit of hindsight that many believe he should never have left in the first place. If Desmond thought as much, he did not let on.

‘He didn’t impart that to me,’ O’Neill smiled. ‘I don’t know. My conversations with Dermot are actually really sort. He just expects me to jump.’

Come Saturday, those who worship the ground he stands on will hope to see him flying through the air again while celebrating a goal.

Back in the old routine against Dundee United, he hopes, at the place where he and his old pal shared so many extraordinary times. Robbo would approve.

‘Honestly, it has been fantastic for me in many aspects,’ O’Neill added.

‘What else would I be doing? A stupid coffee on the King’s Road. And probably just moaning, which I spend most of my life doing anyway.’