Sunday's late 2-1 Euro 2024 final defeat to Spain was the latest heartbreak for the Three Lions, who also lost the Euro 2020 final to Italy on penalties, under Southgate.

But Cooper has seen his impact first hand having guided England Under-17s to World Cup glory when they beat Spain 5-2 in 2017.

Cooper followed Under-20 World Cup success when Dominic Calvert-Lewin's goal had given Paul Simpson's side a 1-0 win over Venezuela in South Korea.

The triumphs came five years after the opening of St George's Park and six years after Southgate toured the country, following his appointment as head of elite development, discussing the Football Association's grassroots review.

"He was the most integral part in what was a huge change at the FA and how the national team operated," said Cooper, speaking to BBC Sport before Sunday's defeat.

"There was a feeling of a need for change and Gareth, along with Dan Ashworth were the real drivers. I wouldn’t say we started from scratch but we looked at everything, the pathway from under-15 to the seniors and the objectives we set.

"We changed the games programme, how we run the camps, who we wanted the teams to play and the culture. We knew it was an important time and it’s proved to be that."

Southgate became England Under-21s manager in 2013 before replacing Sam Allardyce as senior boss three years later.

He has been credited with changing the perception of the squad and the culture but Cooper stressed Southgate's leadership went deeper.

"He was the Under-21s coach but with the responsibility of all the junior national teams and we really stripped it right back," said the former Swansea and Nottingham Forest manager. "If we weren’t careful at that time, we were going to get left behind,"

"We needed to make sure we stayed ahead of the curve. It was an important time -the DNA was implemented and it covered everything from top to bottom.

"Initially, it was the under-21s. Players were desperate to come and play for England. The under-21s tournaments are in the middle of June and that could be difficult for players but they were crawling to come.

"Gareth has taken that into the senior side. Everyone underneath that, we could then look at the top of the tree with Gareth and the senior team and see everything was becoming aligned."