Gareth Southgate revealed Kyle Walker would not automatically regain his England place after the Manchester City defender was surprisingly overlooked for the upcoming Euro 2020 qualifying double-header.

Having finished third in the inaugural Nations League this summer, the Three Lions' attention returns to European Championship qualification with home matches against Bulgaria and Kosovo.

Southgate named an expanded 25-man squad for September's Group A fixtures, with Alex Oxlade-Chamberlain and Harry Winks recalled as uncapped Mason Mount and James Maddison were brought into the squad.

Aston Villa defender Tyrone Mings was the surprise inclusion on Thursday, with World Cup semi-finalist Walker the shock exclusion as Kieran Trippier returned and Aaron Wan-Bissaka received his maiden senior call-up.

Southgate explained his rationale and said he had spoken to Walker about the decision, although he also said that, if other right-backs impress, the 29-year-old would not necessarily walk back into his next squad.

"We tracked him very closely last year," Southgate said of Wan-Bissaka following his maiden call-up.

"We thought he had an outstanding season last season, but we wanted him to stay with the Under-21 group.

"He's adapted very well and very quickly to a high-profile move. And playing in front of 70,000 fans, that brings intensity and pressure.

"We're looking at him and Trent (Alexander-Arnold) and that's the reason on this occasion that Kyle Walker isn't with us, we feel it's an opportunity in particular to have a look at two young players.

"Kyle has started the season really well, so I've explained to him the rationale for the thinking."

Asked if he had told Walker that Alexander-Arnold and Wan-Bissaka were now ahead of him in the pecking order, Southgate replied: "No, no I want to have a look at them. But you know it depends on how well everybody does.

"But absolutely, I have not said to Kyle that that's it. I think that it was a bit different with (Ashley) Young last year, where we recognised that we were going to have to move forward and unless we were in real difficulty, we wouldn't go back."

Asked how Walker took the news, Southgate said: "I think he understands the thinking and I have a close dialogue with all of the players that are in the squad and particularly those that aren't in the squad this time.

"I've spoken with all of them to make sure they're very clear as to the reasoning why.

"As I said, in most of those cases they've missed a chunk of pre-season and the beginning of the start of the season, so that was pretty obvious for them.

"But we've got competition for places.

"I talked about only having eight matches ahead of a European Championship squad announcement – and we've got a depth of talent now because we've approached it slightly differently to look at younger players.

"It's increased the pool that we can pick from, it means that we lack some experience in a lot of positions but we've got to keep evolving as a squad and as a team.

"We've had a two-year period of progress and constant improvement I think.

"But we can't stand still and there are young players coming through that we might not see the best of in the next two years actually.

"Probably two years ago, we waited until we had qualified and then evolved.

"I think during the Nations League, we did it as we were going along and we think that's the right route to go at this moment in time."

Southgate's selections have always had an accent on youth and a view on progress.

The England manager is a long-standing admirer of Mount and believes the Chelsea playmaker has been "one of the outstanding players" of the season so far, while Leicester's Maddison is another exciting talent.

More experienced figures like Fabian Delph, Eric Dier and Dele Alli and John Stones would have been pushing for inclusion were it not for injury, while the latter's absence opened the door to former non-league player Mings.

"I watched him last year and I wanted to see how he adapted to the Premier League and a different level of forward," said Southgate, who brought back Nick Pope for out-of-sorts Jack Butland.

"He's an interesting case because he's got into the game a bit later than some others, he hasn't played as much as a centre-back.

"You know, left-back at Ipswich, (he got a) bad injury at Bournemouth, so there's a lot of room for improvement with him.

"But, actually, I really like his leadership qualities, I think he's an outstanding athlete, very composed with the ball so I'm looking forward to working with him because we see a lot of potential and room for growth given the number of games he's actually played."