John Barnes feels England "may have become a bit cocky" and that Friday's defeat to the Czech Republic can work to their advantage in terms of guarding against complacency.
Gareth Southgate, who has guided the Three Lions to the World Cup and Nations League semi-finals since being appointed as boss in 2016, saw his side beaten 2-1 in their Euro 2020 qualifier in Prague.
It was the first time England have lost a World Cup or European Championship qualifying match in 10 years.
Former England winger Barnes told the PA news agency: "It wasn't the greatest of performances, but it terms of the consistency they have shown over the last two years they have been fantastic.
"I think what helped was that from the outset with Gareth Southgate, we were told we have to give them time to develop and support them. We weren't putting any expectations on them, then they played with freedom and showed what they can do.
"Maybe subconsciously because of what has happened to them in the last year or so, we are now saying we are going to win the Euros, that they are fantastic, and maybe subconsciously they kind of took their eye off the prize a bit and may have become a bit cocky.
"I don't think it was a conscious effort and I really believe last night can work in our favour in just bringing us down to earth, to say 'we're not the finished article, we still have a lot of work to do, let's continue to work with humility.'
"I think because of the success they've had, they have probably got a little bit complacent. So this is not a bad thing to happen now. It is just a little bit of a wake-up call for us to maybe concentrate on trying to be a little bit more together and humble."
Barnes thinks England, who remain top of Group A, need to defend better as a team.
"We need everybody to work harder to help the defence," the 55-year-old said.
"I think that was apparent even when we won 5-3 (against Kosovo in the previous match). For me, if you talk about one place where we need to improve, it's not in our defence in terms of the back four, it is the way we defend as a team."
England's next match is against Bulgaria in Sofia on Monday, and there has been plenty of talk about the potential for racist abuse towards the visiting players in that match.
Southgate has talked about how "everybody is clear" with regard to UEFA's three-step protocol for such situations, while England striker Tammy Abraham has suggested the team could defy that by making their own decision to walk off the pitch.
When asked about that, Barnes said: "What England should do is go and win the match, play the game and deal with whatever happens (when it) happens, rather than try to preempt something negative.
"I'm not a fan of walking off the field, but if that is what they have decided to do, that is what they should do if they feel like that is the solution. I don't think that is the solution, but if they decide as a group that is what they want to do, then that is what they should do."
Barnes was speaking at Villa Park, where his former England team-mate Cyrille Regis' induction into the National Football Museum's Hall of Fame was being marked.
Barnes presented a Hall of Fame award to Regis' widow Julia and his brother Dave during a 'Strike A Change' event, the flagship mentoring programme of the Cyrille Regis Legacy Trust, the charity that has been launched in his memory.
Regis, who died in January 2018 aged 59, blazed a trail for black players in Britain during a career that saw him play for West Brom, Coventry, Villa and Wolves, and make five international appearances.
Barnes said of Regis: "Of course he was one of the first black players to play for England and a pioneer – however, just take that aside and look at his ability as a footballer, and he was an incredible footballer. As a human being he was humble, a fantastic man.
"It is a worthy honour because he was someone who had so much humility, so much talent, and in the face of adversity in the 70s when black footballers had to endure so much, he did it with class, he did it with style.
"He was empowered to know he was as worthy as anybody else, didn't let anything get to him, and of course with his legacy, he is now trying to put back into the community."
:: Cyrille Regis is the latest legend to be inducted into the National Football Museum's Hall of Fame. For further information: https://www.nationalfootballmuseum.com
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