Hart was axed from Manchester City upon Pep Guardiola's arrival in the summer, joining Serie A side Torino on a season-long loan, because the Catalan coach wanted a goalkeeper who was comfortable in possession.
During Hart's time in Italy the 30-year-old shipped 58 goals, with only Pescara’s Albano Bizzarri conceding more in over the same period.
Urbano Cairo, president of the Turin side, has since told the press that he had not expected Hart to make so many mistakes, but Three Lions boss Southgate has described the out-of-favour City shot-stopper's impact with the national side as 'excellent'.
“I read the comments of the president, but frankly that could be related to the fact they know they can’t keep him," Southgate said. “For me, it’s been a real positive. He had to make a quick decision on where he played and he’s seen a different league.
“From our point of view, he’s been asked to play out from the back which I think he’s dealt with it very, very well.
“His impact for us has been excellent. And he’s recognised that he’s missed something this season as regards the level of games and the environment he’d been in previously.
“He’s another player who wants to be the best he possibly can and he’s pretty self-critical.
“But he’s got that drive to be a top player. It will be interesting to see what happens for him in the summer.
“He’s been asked to play with his feet this season. They play out in quite tight areas.
Hart's future remains unclear, with City set to seal the signing of Benfica goalkeeper Ederson to rival Claudio Bravo at the Etihad Stadium.