Colwill has been named in Gareth Southgate’s squad for the first time ahead of Saturday’s European Championship qualifier against Ukraine and next Tuesday’s friendly with Scotland.
The 20-year-old has started all five games under Mauricio Pochettino and his call-up caps a whirlwind year, which has seen Colwill establish himself in the Premier League at Brighton and win the Under-21 Euros before making the breakthrough at his boyhood club.
John Stones, Tyrone Mings and Conor Coady are all injured, while Harry Maguire is in the squad but remains on the fringes at Manchester United and Eric Dier has been frozen out at Tottenham, leaving opportunities at centre-half wide open.
Colwill said: “Playing for Chelsea, one of the biggest clubs in the world, it’s got to be an aim to be in the England team come the Euros. There’s still a long time until that comes, so I need to keep pushing myself.
“Every time you come here it’s an opportunity to impress Gareth. It’s like any career, you’ve got to impress and hopefully I get the chance to. Training with the squad in June [ahead of the qualifier against Malta] was a big blessing. I enjoyed it so much and obviously getting formally called up now is amazing, a dream come true.
“When I first joined Brighton I wasn’t playing, and then Graham Potter left and [Roberto] De Zerbi came in, and I still wasn’t playing for a while. It was tough, but you have to keep your head down, keep working hard, and I think that’s what I’ve done. It’s all worth it in the end, but now it’s about keeping going.”
Colwill singled out Adam Lallana, who is currently with England’s U-21s in a coaching capacity, as someone who had helped him through that tricky period.
“I am a chilled person and sometimes I need someone to give me a bit of a push,” Colwill said. “And at first I did not really understand why he [Lallana] was always on me. But then once it clicked in my head, I realised that he was only trying to help me. I was lucky to play alongside him. It made me wake up a bit and realise the opportunity I have got and that I cannot waste it.
“He was always putting his arm around me, the same as Lewis Dunk. At Chelsea, I have Ben Chilwell and Thiago Silva, leaders in the team for a reason. Their job is to help the young ones and I have had that. I’ve had the best.”
Colwill also credited Pochettino with his continued development, and said he could “guarantee” he would continue to improve under the Argentine.
“Working with him, I know I’m going to improve,” Colwill said. “He’s such a good manager and he will push me, that’s what I need. I need someone there to give me that kick up bum and say, ‘Keep going’. That’s what he does.
“The big thing for me is on the first day I came in, him putting an arm around me and showing me that he respects me as a person and also as a player. That allows me to work my hardest and makes me want to play my best for him.
“That’s a big difference, him showing that there are two sides, whereas the majority of managers may just look at you like a footballer, which he doesn’t. That helps me play my best football.”