Arsène Wenger was not the first foreigner to manage a top-flight English football team. But when Mr Wenger arrived as Arsenal manager in 1996 he may as well have been from Mars – an unheralded French manager with a spotty playing record and strange ideas about diet. Players and fans were suspicious. Yet as he announces his retirement after 22 years at Arsenal, Mr Wenger and his ideas now seem part of the footballing furniture.

His previous job had been managing a club in Japan, an utterly exotic place in footballing terms. The few non-British managers preceding Mr Wenger had either been great ex-players or monumental failures or both. Mr Wenger could boast only an undistinguished career. Worse still, he had a university degree, in economics, at a time when the rare British footballer with an A-level was nicknamed “Professor” in the dressing room. But right from his first press conference, in which he extolled the virtues of broccoli in a player’s diet, he managed to win over even the doubters of the footballing media. “Arsène spoke for 50 minutes, and we were spellbound,” recalled one journalist.

His early triumphs were the products of excellent circumstances, which he adroitly exploited. Strategically, Mr Wenger was buoyed by the wave of television money coming into the Premier League, and used it to sign talent across Europe – unleashed by the Bosman ruling in 1995. Tactically, he revived a rock-solid defensive unit inherited from previous managers, and welded midfield talent to the attacking genius his scouts had spotted in Thierry Henry.

A revolution followed. Out went unfocused training techniques and the binge drinking that bedevilled English clubs and ruined careers, and in came salads, fitness and coaching that emphasised pace and movement. Out went a search for players focused only on Britain and Ireland, and in came scouts criss-crossing Europe, exploiting Mr Wenger’s contacts and knowledge to assemble a formidable squad. And out went the casual racism that infected football with myths about foreign black players lacking “bottle”, kicked into touch immediately by Mr Wenger’s signing of Patrick Vieira.

His revolution was immediately successful – far beyond fans’ wildest dreams, with a double triumph of Premier League championship and FA Cup titles arriving in 1998, and repeated in 2002. But Arsenal’s only league title since then came in 2003-04 – an invincible season – and as the gap from glory grew longer, the complaints from fans grew louder.

Many feel he held on too long. Mr Wenger’s later years saw much pretty football played, but he never seemed to uncover and develop talent as he had done in his earlier years. The lack of money undid him: the tidal wave of cash from super-rich owners, fuelling Chelsea and Manchester City, relegated Arsenal to footballing middle class. But he did pave the way for that wave, by making foreign ideas and foreigners happily at home in English football.