During a little more than two years at Celtic Park, the Norwegian never did quite manage to disturb the notion that he was too slight, too diffident almost, for what was demanded of him.

But then we might also wonder if we ever truly understood him, or even took the time to see beyond the assumptions that gathered so effortlessly around Brattbakk. During his spell in Glasgow, he sought to learn Gaelic and, having earned an economics degree and worked as an accountant back home, he once pored over Celtic’s balance sheet with a zealot’s glee. Yet these were considered quirks of his character while he was faltering in the more pressing business of scoring goals for the club. Signed from Rosenborg for £2 million, when he was sold to FC Copenhagen for £650,000 it was as if his diminishment could be measured accurately.

In one sense it could, of course – that of the absolute figure of goals scored. Brattbakk arrived at Celtic as a striker of unequivocal consistency in Norway and with a record of four goals in just six Champions League games. This reputation suggested a refinement, but instead it began to feel like a curt accusation. It was five games before he scored for Celtic and what he came to resemble was a sense of uncertainty, a kind of doubt.

We could see it in his pale face and although his movement was always swift and insightful, there was often a bewilderment to his expression, as if at that moment when he most needed to be decisive, he was instead detached. With his neat blond hair, the narrow silver-rimmed glasses he wore off the field and the donnish air he carried, Brattbakk appeared too meek to convince in a place where reputations are formed with an instinctive and savage brusqueness.

“The biggest mistake I made was meeting the press for the first time with glasses on,” he joked. “Celtic were so proud that they’d gotten hold of a goalscorer and there I came, 150lb and glasses. I even had all my teeth. I was just me, but people had expected to see something different.”

There is an astuteness in his humour, but if Brattbakk had plundered a haul of goals, or at least not been alarmingly wayward in so much of his finishing, this impression of him as a kind of wisp of ambiguity would definitely not have established itself. As Georgios Samaras and Marc-Antoine Fortune are finding this season, verdicts in Glasgow tend to be written with such certainty that they might as well be carved into stone.

“I don’t think my confidence suffered, you have spells through your career that are good and bad,” Brattbakk says. “I wish I could have played better, but I’ve no regrets from my time in Glasgow. In hindsight you can maybe say that with my style of playing Celtic wasn’t the optimal place to come to, but I tried to adapt. I don’t think I could have done things much differently.”

Perhaps in a way, nobody at Celtic would have wished him to, either.

Brattbakk eventually scored four times in one game, against Kilmarnock, and struck the second goal in the 2-0 win over St Johnstone that clinched the title for Wim Jansen’s side and finally halted Rangers’ quest for 10-in-a-row. But his most significant contribution was as a foil, in the perceptive quality of his runs and distribution, for Henrik Larsson. The Swede really emphasised Brattbakk’s apprehension with the stunning consistency and luminosity of his own contributions, but was always quick to acknowledge the enabling influence of his strike partner.

“I always had respect for him and he’s the best player that I ever played with,” Brattbakk says. “But that’s one of the reasons why I felt I didn’t perform as well, because Henrik over-performed in every game. After a while, people started to compare all the strikers with Henrik and that’s a tough comparison.”

Brattbakk eventually returned to Rosenborg and rediscovered the sharp acuity of his finishing and he remains the Norwegian league’s all-time top goalscorer. He even struck twice when Rosenborg met Celtic in the Champions League in 2001. But the game soon began to feel insignificant and when he retired three years ago, Brattbakk turned to an old passion, having begun flying lessons before moving to Celtic.

He completed his studies then spent one year in America gaining his commercial pilot’s licence and now flies for the Norwegian coastguard and pollution control agency, conducting surveys. He admits, though, to a renewed interest in football, and a belief that he will return to the game, probably in the boardroom at Rosenborg.

“When I fly, it’s a way for me to be able to leave the rest of the world for a couple of hours,” said Brattbakk. “I probably couldn’t have found a job further away from football. The biggest difference is that when you play the game, you can make mistakes and not afford to correct them. But when you fly, if you make mistakes then you simply cannot afford to not correct them.”

He never did fit the mould we set aside for him, but then perhaps it was our imagination that was lacking.