"Pep is always trying to get me to bring a guitar to a big game, so I can play in the dressing room afterwards," Gallagher explained to BBC Sport.

"I went into see him after the Real Madrid game [in the semi-finals] and told him I couldn't be at the FA Cup final or the Champions League final and, honestly, he gave me a look of utter disgust.

"It was with real contempt, as if to say 'well what the hell are you doing instead then?'. I said 'I am on tour' and he said 'cancel it!'.

"I said 'I can't, I've sold the tickets now', and he was like 'ahh, get out' and he almost launched me out of his office. He probably treated me the same way he did Joao Cancelo when he got rid of him in January."

'An error of admin'

Gallagher, whose High Flying Birds released their latest album, Council Skies, on Friday, is touring the United States when City play Inter Milan in Istanbul and he has already missed the club's first two victory celebrations of what has become a sensational season.

"I wasn't at the Etihad for the Premier League trophy lift either," he added.

"I'd made plans I couldn't get out of for the Sunday of the Chelsea game and then, when Arsenal lost at Nottingham Forest the day before, I was like 'wouldn't you just know it… Arsenal, I can't rely on you for anything!'.

"We started our tour last week so I missed the FA Cup final too. Everyone has been asking 'are you going to be in Istanbul?' and I have to reply: 'no, there has been a mistake', or an error of admin as they put it.

"My management are told never to book any gigs anywhere in the world around the Champions League final, in case City get there.

"It usually falls around my birthday, at the end of May, so when this tour was put in front of me, and it's down to start in the US on 2 June, I am thinking great, push the button, it's done.

"But then a few months back I suddenly thought oh no, I forgot to factor in the World Cup and how that has pushed everything back. I saw the Champions League final was 10 June - it's never been held that late before - and I couldn't believe it.

"Then you think well, we are not going to get there anyway, so who cares - we will probably go out in the quarter-finals again - but then we kept winning. We were getting closer and closer and I was thinking 'oh no!'.

"To be honest though, I've been there to see us win so much now that I don't care too much about not being at this one, as long as we win it."

What would define greatness?

Noel and Pep celebrate City's Premier League title triumph at Etihad Stadium in 2018, at the end of his second season in charge. Guardiola's next chance to see Gallagher play live might be in August when he plays a homecoming concert at Wythenshawe Park in Manchester at the end of August.

Gallagher has seen City lift plenty of silverware since Guardiola took charge in 2016, with his side collecting five Premier League titles, two FA Cups and four League Cups in the space of those seven seasons.

So far, the Champions League is the only major prize to elude the Spaniard during his time at Etihad Stadium - but Gallagher says it is nonsense to label him as a failure if he doesn't change that on Saturday, or in the future.

He explained: "I always put it this way; if the Champions League or European Cup defines greatness then are Steaua Bucharest [who won it in 1986] a great team?

"And Porto [who won it in 2004], are they European elite? Are they heck - they won a cup competition. Good luck to them and all that, but that's what this is.

"The best teams don't always win cups, do they? Arsenal are lauded as one of the great British clubs of all time, and their Invincibles are called one of the best ever teams, but they never won the Champions League and no-one says Arsene Wenger was a failure, right?

"As well as what Pep has won, when you look at how he's done it, and the influence he has had on our game, then for anyone to even suggest that he has failed in English football if he doesn't pick up the Champions League is an idiot, a total idiot.

"I go and watch my kids play football a lot and when you wander around the pitches on a Sunday morning when there are loads of games going on, every young coach has their teams playing out from the back.

"Knock it long and get it in the mixer? There is none of that. Pep has influenced every young football coach and therefore they have influenced every young child who plays football, and that's just a fact.

"That in itself is a much greater legacy than the Champions League, even though he will win it with us, hopefully on Saturday.

"Inter will give us a tougher game than Manchester United did at Wembley and I am expecting it to be a long night, but I do think we will beat them."

Guardiola's greatest season?

Gallagher was the first person to interview Guardiola when he took charge at City in the summer of 2016, and has enjoyed every evolution of his team since then.

"When we played for so long without a recognised striker because Sergio Aguero was out injured, then we were waiting for Erling Haaland, I think Guardiola enjoyed the fact that we won the league with a false nine," Gallagher said.

"He perfected that, and now he has done this thing with John Stones going into midfield - a centre-half stepping up like that is mad. No-one else comes up with this stuff, no-one.

"I was at the 4-0 win over Real Madrid last month and it felt like we had 13 men on the pitch because Real weren't getting near us.

"It all just goes to show how Pep never stops thinking. Next season he will come up with something else, because someone will man-mark Stones.

"I remember speaking to John after the Arsenal game a couple of months back when he played in the middle of the field and scored, and I said 'bloody hell mate, how many positions can you play?'

"He said 'to be honest, I haven't got a clue what I am doing - Pep just tells me I am going to play in there and do this and I say OK'.

"It feels like Guardiola kind of believes in the players and what they can do more than they believe in themselves sometimes, and it works.

"What he's done down the years is fascinating, but for me this has been his greatest season.

Guardiola wants Premier League financial charges resolved 'as soon as possible'

"He had to bed Erling Haaland into the team, get rid of Cancelo because of his sulking and do something different at the back, then deal with the doubts about whether his captain, Ilkay Gundogan, is staying or going… all while chasing down Arsenal when they were so far in front.

"The players have been brilliant of course, but Guardiola did all of that and also had to guide the club through the backdrop of all the charges from the Premier League.

"There was also a point [after the Tottenham game in January, see video above] where he basically called out everyone at the club - the players and the fans - and I was like 'wow, he's never done that before'.

"But here we are; champions again, the FA Cup in the bag and one game away from the Champions League and the Treble. I don't know how he keeps doing it, but it is bordering on voodoo."