Captain Alastair Cook has hailed Graeme Swann's contribution to the England team both on and off the field following the spinner's surprise retirement.

Swann announced on Saturday that he was quitting all forms of cricket, despite there being two matches of the Ashes series remaining, with England trailing 3-0.

Cook has admitted that the timing of the 34-year-old's decision was courageous considering the backlash that he has received after hanging up his boots during the middle of their tour Down Under, but agrees with Swann that his giving up of the game comes at an appropriate juncture in his career.

"Graeme has had a fantastic career," Cook told reporters. "He has been an integral part of our success, both on and off the field. He is going to be missed hugely. But he just knew this was the time.

"He'd given his all in the England shirt and can be very proud of his achievements. He can also take great credit for the way he managed to bring that more relaxed atmosphere to the team. I noticed straightaway he made people enjoy playing cricket for England maybe more than when I first started.

"I think it is a very brave decision for him to do it now, in terms of what he is giving up and everything that goes with playing for England. But I think he knows deep down, after speaking to him, he had no more to give - and he didn't feel he could perform to the standards that he set for himself."

Swann is England's second-highest wicket-taking spinner in Test history, having picked up 255 dismissals at an average of 29.96 in his 60 matches, fewer than only Derek Underwood.