Around the Westminster village yesterday politicians, journalists, waitresses and on-duty policemen were as startled as everyone else to learn that their old friend, John Sergeant, had withdrawn from Strictly Come Dancing.

But many of them have been equally startled by Sergie's elevation from the BBC political rota to prime-time celebrity status on Saturday night TV. Was this lovable, Pickwickian character naively stumbling into the limelight the same sharp-elbowed, often grumpy colleague they remembered?

In the excitement over 64-year-old Sergeant's amazing success on SCD, what has often been overlooked is that he was a comic actor before he was ever a political journalist - an Equity member before an NUJ member, as he sometimes puts it, appearing in an early Alan Bennett hit, the TV revue On the Margin, at just 22. Career uncertainty later edged him back into journalism via the Liverpool Daily Post.

His Westminster career saw tension between seriousness and mischief. When Alastair Campbell told travelling reporters that Tony Blair would be coming down the plane to brief them, Sergeant said: "Couldn't he wait until the film finishes?"

But in the highly competitive world of BBC news reporting he was sometimes regarded as an uncollegiate colleague with whom it could be hard to tango.

"It's a mistake we've all nearly made," Sergeant is said to have remarked when his then BBC boss, Robin Oakley, slipped up on air. A reputation for being difficult contributed to his not getting the BBC political editorship when Oakley stood down.

The polymath Andrew Marr got the job and, after talk of his taking over the BBC's Antiques Roadshow, Sergeant spent his pre-retirement years at ITN.

But Sergie has had the last laugh.

Already a familiar figure on lecture and cruise ship circuits, his skilful handling of his exit from SCD will ensure lucrative celebrity status for some time to come.