Maguire’s availability for the Euros has been a major talking point since sustaining a high ankle sprain on May 9.
All eyes will be on a partially filled Wembley on Friday for an eagerly-anticipated Auld Enemy showdown that sees the Three Lions attempt to reach the last 16 and dent the wounded Scots’ hopes.
Steve Clarke’s men can call on Kieran Tierney after opening Group D with a 2-0 loss to the Czech Republic, while England are able to turn to a key returning figure of their own after beating Croatia 1-0 on Sunday.
Maguire’s availability for the Euros has been a major talking point since sustaining a high ankle sprain on May 9, ruling him out of the rest of Manchester United’s campaign.
Southgate said his return to fitness would be a “bonus” after selecting him in his 26-man squad, yet the centre-back has made such impressive strides that he is back available to face Scotland.
“Yeah, Harry will be involved tomorrow,” the England manager said.
“The decision we’ve got to make is whether he’s ready to start but we’ve been really pleased with his progress.
“He’s trained with the team for four or five days now and had no reaction.
“Of course, each session that he’s involved with he gets more confident and I think he’s on a really good path, so of course we want everybody available.
“It causes difficult decisions but at the moment, this morning, on this training pitch we had 26 players training and that’s a great situation for us to be in.”
England head into Friday’s encounter knowing they will be through to the last 16 if they beat Scotland and would be confirmed in the top two should they win and Croatia fail to beat the Czechs earlier in the day.
Thousands of Scottish fans have descended on London as anticipation builds ahead of just the second ever major tournament meeting of international football’s oldest rivals.
Southgate started in the other as Paul Gascoigne’s stunner wrapped up a 2-0 Wembley group win at Euro 96 – a “fantastic occasion” that sparked wild celebrations that the England boss would love to repeat.
“For me it’s always about creating those moments for our fans,” the former defender said. “There’s two parts of it as a manager.
“One is to get the best out of the players and help them to achieve the maximum level possible and the other is to give the fans a day that they are celebrating and enjoy and they go home happy.
“There’s not really a lot else that’s important. We know what it would mean for our supporters to go home with a win tomorrow night.
“We know that would help to build more excitement and anticipation for the games that follow. That’s absolutely high on our priority list.”
While victory would be great on a number of levels, Southgate wants his players to approach Scotland “like any other game of football” and not get caught up in the hubbub surrounding the fixture.
“We of course know that we have to compete because otherwise you can get overrun in any game” the England manager said.
“But our focus has been on solving the tactical problems that Scotland pose with the way that they play, the way they defend and the way they attack.
“Our focus has got to be on performance getting better with every game we play.
“Of course for the fans and for us it is a big occasion but it is another opportunity for three points and our objective is qualification and that is what we have to focus on.
“I thought in the past we have done that well. I thought we did that very well on Sunday.
“Sunday was a big occasion for everybody and with the heat I felt we did that very well.”