Paul McGuinness: 'Belief' is key to England young players' success
Belief is the most important aspect for young players' success, says the Football Association's new national coach developer.
Paul McGuinness, who worked at Manchester United's academy for 23 years, said playing in big tournaments would bolster their development.
"Each time you go further on, you get that belief," he told BBC Sport.
McGuinness was involved in the development of a number of key United players, including England internationals Marcus Rashford and Danny Welbeck.
He also coached the team that won the FA Youth Cup in 2011, which featured midfielders Paul Pogba and Jesse Lingard.
McGuinness, 51, told BBC Sport: "The summer proves it is not one group of players. It is a series of teams who have done very well.
"Belief is a big thing. That is exactly what these England players will have. 60,000 in India in a World Cup final - you are proving to yourself you can do it on the big stage."
Prior to this year, the England U17s had never before progressed beyond the quarter-finals in the global tournament.
Head coach Steve Cooper said that their victory reflected the "good work" being done in youth development, and that youth sides were "heading where we want to go".
England won the European Under-19 Championship with a 2-1 victory over Portugal in July, while the under-17s lost on penalties to Spain in their European Championship final in May after conceding an injury-time equaliser.
McGuinness added: "One year at United, they won the Premier League, reserve league, under-19s and under-17s. It creates a massive belief and a consistency.
"It is not a fluke where one team has won a tournament, we got three or four in finals. That creates great belief. It can snowball."
McGuinness said that players' success at international level would lead to more Premier League opportunities.
"Phil Foden was the player of the under-17 tournament - that means he is closer to getting into the Man City team and 55,000 at the Etihad," he said.
"With these successes, [England manager] Gareth Southgate might be thinking 'can I bring some of these players along?' or have one or two in the squad because they are on a roll. If they are put in, they may well do well.
"There are actual examples. Look at Marcus Rashford - one minute he is playing for the under-18s, by the summer, he is playing at the Euros."