Gareth Southgate has been strongly backed by Football Association chair Debbie Hewitt following England's disappointing Nations League results, which included a 4-0 home defeat to Hungary.
That embarrassing loss last week even sparked a debate over whether the England boss should be sacked ahead of the World Cup in Qatar, which starts in November.
But Hewitt hailed Southgate's role in transforming the team's fortunes on the pitch and instilling a healthy culture off it.
The 51-year-old last year took England to the final of Euro 2020, three years after reaching the semi-finals of the World Cup in Russia.
"My personal opinion on Gareth is that he is, by the facts on the pitch, the most successful England manager we've had for 55 years," said Hewitt, who took over as FA chair in January.
"The bit people don't see as much is the Gareth at camp and the culture he's created.
"Certainly prior to Gareth being the manager of England, there was not the pride of wearing the England shirt. There were the club rivalries we'd read about. The players not getting on.
"He's changed that beyond recognition and I've seen that first hand."
Hewitt praised Southgate's willingness to take responsibility for setbacks.
"It's refreshing working with somebody like that because that openness to learn is quite remarkable and quite unusual in any sphere," she said.
Hewitt added that any debate over the timing of the decision to award Southgate a new contract prior to the World Cup was a "red herring".
He signed a new deal in November which keeps him in post until the end of 2024.
"I don't think we would be discussing (the contract) had we not had the recent series of games," said Hewitt. "Clearly we did that (agreed the new deal) with proper discussion and thought.
"The fact that there's been a stumble does not make us automatically say 'should we have given him a contract?' It is a red herring.
"We have confidence in Gareth for all the reasons I described and I think that's the important thing. And it's particularly important going into the biggest tournament."