He has affection for Celtic and for St Mirren too, but is currently impressed by only one of them. St Mirren would do well to avoid McGarvey's assessment of their chances: he doesn't think they have any. How could they have, when he sees Celtic as the most improved club in world football?
McGarvey was a charismatic, prolific scorer for Celtic between 1980 and 1985. He was brave then and he isn't shy now. Talking yesterday at an event to publicise the game, he brought his usual candour to the table. Celtic had been a mess when Neil Lennon took over in 2010, he said. Very briefly he wondered if Lennon might be hopeless, but generally he's been his biggest supporter. He was glad Tony Mowbray was sacked because it was for his own good. But now, with Lennon in for Mowbray and Ian Bankier replacing Brian Quinn as chairman, McGarvey cooed at how his old club was being run.
"By God, Celtic have got some scouting system," he said. "I think Celtic are the most improved club in world football. The scouting system is second to none. They have bought and sold well. They sold Aiden McGeady for £8m and, don't get me wrong, he is a good player, but Gary Hooper scores goals. As far as I am concerned, if you want Hooper it's at least £12m. They sold McGeady and Ki [Sung-Yueng], got £15m for them and bought wisely. They got Victor Wanyama for £900,000 and now he is worth £15m. Now, through keeping their best players over the last year, and also buying and selling wisely, it's put them into a position where they've done well in the Champions League and made over £20m."
McGarvey, now 56, was a rising star when Liverpool signed him from St Mirren in 1979. He languished in the reserves – that was the way of things at Anfield – until frustration accelerated a move back to Scotland and to Celtic in 1980. He can speak with authority on swapping Scottish football for English, then, but his circumstances were entirely different from those faced by Gary Hooper. McGarvey is unimpressed by the idea of Hooper going to Norwich City, who have confirmed interest in Sporting Kansas City striker Kei Kamara.
Still, neither the size of the bid, £5m, or the club itself, was to McGarvey's liking. "If he wants to go down there, fight relegation and win the Capital One League Cup, that is fine. And if he is getting enough money for that; it's a short career. He won't need to work the rest of his life. That's important. But if you have ambition it's different. If it was Manchester United bidding . . .
"Celtic won't take £5m for him anyway. When you consider Daniel Sturridge went to Liverpool for £12m; he can't get into the Chelsea team and Chelsea can't get into the last 16 in Europe. Hooper has been scoring in the league and the Champions League to get Celtic into the last 16. For me, Hooper's value starts at £12m. The two best centre-forwards in England are Luis Suarez and Robin van Persie: fantastic players. They are worth £30m. So how is Hooper worth only £5m? He probably has a chance now, as with Fraser Forster, of getting into the England team."
McGarvey won two league titles, two Scottish Cups and one League Cup with Celtic before moving to St Mirren, where he added another Scottish Cup in 1987. He would take pleasure from either side winning on Sunday but cannot envisage anything but a Celtic victory. His admiration for Lennon is huge. "You have to remember the mess he took over and what he's done. I've supported Neil from the beginning and I took a lot of stick when he wasn't doing well, from people saying 'what are you supporting Lennon for, he's hopeless'. At one stage I was beginning to think 'I think he is hopeless' but I still backed him. I don't see anyone lining up to criticise him now.
"I thought he was the only man for the job. I was glad Mowbray got the sack: not because I wanted him to get the sack, but because the poor guy was in utter pain. You could see it in his face. He was going into Parkhead in the morning and the players didn't like him, he was trying to take the team and they weren't bothered, he'd lost the dressing room, he was reading the papers and getting stick from the fans, then he was going into the boardroom and they didn't want to talk to him because he was doing so poorly. He was a nice guy but I felt he should get the sack because he was in pain. He had to go away for a few months and just rest. I just felt the job was too big for him.
"Celtic are in the last 16 of the Champions League so they are one of the best 16 football clubs in Europe just now and St Mirren have just played their poorest game and lost 4-1 to Ross County. The only thing that can beat Celtic is them being over-confident and I don't think Neil Lennon will let that happen to the players. St Mirren have almost no chance of winning."