The former Ibrox prospect has been tipped to be the best player of his generation after moving to London last summer in a £500,000 move when Chelsea beat off competition from Manchester United, Manchester City and Bayern Munich to land him when he was only 15.

A year on, Gilmour has already clinched four trophies with Chelsea’s youngsters and has been fast tracked into Scotland Under-21s at the Toulon Tournament this week, where he could line up against hosts France today. The Scotland coaching team have been raving about his progress too.

In his first major interview, Gilmour revealed the agonising he had to go through when he quit Rangers to move to London.

Chelsea's Billy Gilmour celebrates his goal in the FA Youth Cup final 2nd leg against Arsenal U18. Picture: Kieran Galvin/NurPhoto via Getty Images

He had been promoted to training with the Rangers first team and the 16-year-old would have almost certainly have made the starting XI, just as his pal Harry Cochrane has done at Hearts.

But he is convinced he can make an impact at Chelsea and has absolutely no regrets about his move.

Gilmour said: “It’s been an incredible year for me. I missed the first four games of the season waiting for paperwork to go through and I was getting frustrated. But I eventually made my debut against Arsenal and scored in a 2-0 win. From there, everything has gone brilliantly. We’ve won four trophies in my first season, which has been amazing.

“At Rangers, I was training with the first team quite a lot. I was only 15 so I couldn’t actually get on the pitch. If I was maybe a bit older when I had to make the decision, it might have been different.

“My friend Harry Cochrane is in Hearts’ first team now and doing really well. If it was later, maybe it would have been a good decision to stay because I’d have been bigger, more developed. But I’m not fully developed yet. If I’d matched myself up against Scott Brown, for instance, he’d bully me for a full game. He’s the best midfielder in Scotland by far so if I had to go up against him, I’d have no chance. Maybe technically, I’d be OK. But in terms of running about and pushing him off the ball – no chance.

“So that’s the way I looked at it. Would I have been ready at that stage? The answer would have been no.”

Gilmour, who has already trained with the first team at Stamford Bridge, recalled the moment when he swapped Ibrox for the bright lights of London. He explained: “I was with the Rangers Under-20s and I played well in a game against Falkirk and the spotlight was on me a little bit. Then I played well against Northern Ireland for Scotland and there was a lot of talk about me in the papers.

“It was a good tournament for me and after it, my agent took a lot of calls. I just wanted to play football. At that age, I never thought that side of things would come until later. But my ambition has always been to go to the Premier League, so I thought I better give it a shot. So far it’s been amazing.

“I spent a lot of time on the decision. It was between Rangers and Chelsea. Most of my family are Rangers fans and I love the club. I’ll always be thankful for everything they did for me. But when Chelsea showed me what my development plan was going to be, I couldn’t turn it down. Everything about the club was incredible.

“If you really know what you want, it’s an easy decision. If boys are hesitant – who say they want it but don’t really – it can be difficult. But my aim has always been to play at the best level. I’ve always wanted to play against older players, get the best coaching, stay behind and do more.

“So when I heard Chelsea came in it was a no-brainer. I wanted to be with the best team. They win the league for fun, have won the FA Youth Cup five years in a row, play in the Champions League. That’s what I wanted to be part of. I want to be winning everything.

“Moving away from my family wasn’t a big deal for me. I’ve always loved being away. Even when I was in Scotland, I’d be staying at digs with Rangers. So it doesn’t bother me and Chelsea are good at allowing me time to come home.”

Gilmour is determined to find a way into the Chelsea first team eventually.

He said: “From next season I’m trying to get into the Under-23 squad and Champions Youth League squad. Then if I am physically developed enough I would try to go on loan or try to push myself into the first team.

“People who say I will never get a chance have never experienced it so it’s hard for them to know. I know it looks like everyone gets loaned out, but you look at Ruben Loftus Cheek who has made the England World Cup squad.

“I know I have to develop physically. I don’t want to be massive and big, I just want to be stronger. I want my legs to be stronger. At Chelsea I’ve been doing about 13K around the pitch. Sometimes when you look at the other team you think ‘oh my God’ but when you’re on the ball it’s fine. It’s quick, which I like. I love one-touch and two-touch football and I love winning headers against big physical boys because they get annoyed at me. It’s the best feeling ever! Coming here has helped me.

“It would be amazing to play for Scotland one day. I love coming away with them, even to squads just to train. Just putting the jersey on is amazing, words can’t describe it.”

Billy Gilmour: '˜Scott Brown would have bullied me if I had stayed at Rangers'