Perhaps, while all we could see was the serene Graeme Swann with the flashing smile and the irresistible one-liner, there was more thrashing around going on beneath the surface than we guessed. It is an extraordinary act to retire in the middle of a series. Captains, very good ones such as Michael Vaughan and Nasser Hussain, sometimes reach the sudden realisation that they can't do this any more. But those in the ranks usually plough on at least to the end of a series.

The sudden retirement of Swann underlines the ruthless brilliance of Australia's Ashes campaign, which hinged on how they were going to deal with the spinner. They recognised that Swann had been a vital component of recent successful England sides since his remarkable Test debut in 2008, when he picked up two wickets (only Gautam Gambhir and Rahul Dravid) in his first over.

In a sense Australia's strategy was a huge compliment. Undermine Swann and England would be rudderless. The plan has been far more effective than Australia could possibly have envisaged. Not only have they knocked Swann out of the park, but out of the series.

The plan was not so well disguised. To Swann's second ball of the series David Warner leapt out of his crease and smashed the ball over the bowler's head to the boundary. All the Australian batsmen, with the decorous exception of Chris Rogers, would follow suit. The assault upon Swann did not just apply to his bowling. The Australians were even more ruthless when he was batting. Swann has always been the sweetest striker of a cricket ball and at Test level a dangerous lower order batsman, who has, by his aggression, rescued many a stuttering innings in the past.

The Australians were never going to let that happen again. Mitchell Johnson and Ryan Harris gave him no opportunities to play his favourite cover drive. Instead they peppered him ruthlessly. It may be that the knowledge that he was struggling to cope with the bat hastened the retirement plans. A slowing of the reflexes is easier to spot with a bat in the hand. Moreover the elbow has been constantly troublesome over the last two years. Swann has not bowled as badly as the figures suggest in this series, but maybe a bit of zip was missing – and a few successful stumpings would have helped.

This is a far from the ideal way to go but his sudden exit should not disguise a brilliant and unexpected England career. Remember he toured South Africa in 1999 as a bumptious 20 year old; he succeeded only in getting up many noses and was then ostracised for almost a decade. By 2008 he knew his trade yet no one anticipated that he would make such an impact. Conventional finger spinners were as out of fashion as hula hoops. They provided insufficient mystery for modern batsmen with their mighty cudgels.

Facebook Twitter Pinterest Graeme Swann (centre) celebrates the wicket of Gautam Gambhir during his Test debut in 2008. Photograph: Indranil Mukherjee/AFP/Getty Images

Swann soon demonstrated that this theory required modification for several reasons: he spun the ball more than most finger-spinners; he was braver than most, too, since he would bowl a more attacking line to right-handers. He would aim a little wider of off-stump than a John Emburey or a Ray Illingworth. This allowed more run-scoring opportunities, but it also gave him greater chances of taking wickets.

With the advent of detailed TV replays and DRS, Swann also recognised the possibilities of lbws that Illy and co could only dream about. Swann tormented left-handers superbly. He ensured that he bowled straight against them and if they missed their forward defensive and were taken on the pad then there was a good chance that they would be given out. Swann became an excellent judge of what was out and what wasn't, though the chances of him exploiting this skill in retirement by joining the list of first-class umpires remain slight.

Above all these skills Swann became a wonderfully streetwise cricketer. He may always seem to be joking off the field; on it he was a pragmatist and an exceptional reader of batsmen. He always knew his field and his plans and he had no hesitation in implementing them, whoever his captain. He also imposed on batsmen; at his best he had that aura, albeit not quite in the Shane Warne class, but he managed to get inside a few heads (though this would always prove more difficult against Australia and South Africa). So they missed some of his straight balls and perished.

Off the field he was generally a delight. In the press room there was always a tinge of relief when it was announced that Swann was on his way. He shunned the usual banalities, could rarely resist that one-liner and generally provided good copy, though nothing quite so sensational as his revelation of retirement in this weekend's Sun on Sunday.

England will be a duller, weaker side without him. In the short term Swann's departure allows Monty Panesar to resume as a Test regular. Down the line it is hard to think of any young English spinner who is anywhere near his standard.

We will see more of him, for certain. There may be an IPL contract now that he is permanently available. Broadcasters will compete for his wit and expertise. And despite the suddenness of his retirement, which leaves Alastair Cook and Andy Flower with another gaping hole to fill, his legacy is secure. Only Derek Underwood among the spinners took more wickets for England. Along the way Swann surpassed Laker, Lock, Titmus, Emburey, Edmonds and Illingworth. He would have settled for that at the beginning of December 2008 when, in his 30th year, he had yet to play a Test.