Chelsea responded with an immediate £6 million bid for Stoke City goalkeeper Asmir Begovic but Abramovich’s decision to let Cech join Arsenal, which conflicted directly with Mourinho’s publicly stated wish, is the source of huge controversy around Stamford Bridge.

Arsenal have struggled with the goalkeeper position during recent seasons but Cech – regarded by both Mourinho and Arsene Wenger as one of the best in the world – will now report for training at the club’s London Colney base next Monday. He has signed a four-year deal worth more than £100,000-a-week and his first match should be the Community Shield against Mourinho’s Chelsea on Aug 2.

"Life doesn’t always turn out the way you think it will,” said Cech, in an open letter to the Chelsea fans. "I thought this would never happen but it is time for me to say goodbye to Chelsea. The club in which I thought I’d hang my gloves and boots one day and finish my career.” In 11 hugely successful years at Chelsea, Cech was part of 13 trophy-winning teams but fell behind Belgium goalkeeper Thibaut Courtois in Mourinho’s pecking order last summer.

"I know I am not at the stage of my career where I want to be on the bench,” said Cech. "That’s why I spoke to Mr Abramovich about me staying in the Premier League and I’d like to thank him from the bottom of my heart for his support.”

Mourinho is now hopeful of signing Begovic although Stoke have rejected Chelsea’s opening offer. They are holding out for more than £8million and are also interested in taking a player on loan next season.

Chelsea still hope to complete a deal in the next 48 hours but they must also reassure Begovic, who would clearly find himself in Cech’s position of understudy to Courtois. Begovic could double his wages at Chelsea – and should also get chances to play in the domestic cups – but may want to see if Manchester United want to make him their replacement if David de Gea joins Real Madrid.

Cech’s arrival will also have big ramifications for Arsenal. Wojciech Szczesny has made it clear that he wants to stay and posted a message on Instagram that welcomed Cech’s signing.

"Delighted to have a chance to learn from one of the best goalkeepers in the world,” he wrote. Colombia goalkeeper David Ospina is likely to feel rather less enthusiastic. Ospina had replaced Szczesny as Arsenal’s number one goalkeeper last season but is expected to join Fenerbahce.

Chelsea goalkeeping coach Christophe Lollichon may now follow Cech to Arsenal. Cech was also wanted by Paris St Germain and, although he said that it had been his "hardest” ever decision, became convinced by Arsenal after speaking with Wenger.

(telegraph.co.uk)