Aside from his official opponents, Clarke will now to keep a beady eye on his supporters. For his campaign bandwagon has just gained an unwanted passenger.
The UK Independence Party, which for years has sternly criticised Clarke's pro-European views, is about to declare its formal supports for his Tory leadership bid.
Their move follows Clarke's recent declarationthat he's changed his mind about the euro, and may lead to UKIP's many noisy supporters infiltrating Clarke's coming campaign events.
"Ken Clarke is a man of great principle and experience, and has support from a very broad range of voters," says the UKIP MEP Nigel Farage. "He says he's the best man for the job and we at UKIP agree wholeheartedly.
"It is thrilling that Mr Clarke has changed his mind on the single currency. During the campaign, he will undoubtedly want to share his thoughts with the electorate on other issues on which he has had a rethink. I will expect his telephone call for advice."
Quite how such support will go down in the Conservative Party wasn't clear last night: at the time of going to print, the Clarke camp wouldn't be drawn on whether they'd accept UKIP's shilling.
* Sol Campbell's love affair with the frizzy interior designer Kelly Hoppen has been through more ups and downs than your average FA Cup tie.
In the past year, the couple have split up, been reconciled, and split up again, affording the Arsenal defender Campbell time for dalliances with both Martina Hingis and the singer Dido.
Now they've got it back "on" with a vengeance, though, and will face the cameras together on Wednesday at the launch of a book called Everything I know About Men I Learnt From My Dog.
Campbell, 30, and Hoppen, 45, are listed as an "item" on the author Clare Staples' guest list for the bash.
"Clare's a former model, and knows Kelly well," says an organiser. "If she and Sol are on the list together, you can presume they're coming as a couple."
Incidentally, Staples' self-help book shows women how to keep their boyfriends in check "using similar techniques to dog trainers".
Pandora says: Good luck, Sol!
* Earlier this year, Jo Brand made a plucky bid to complete the London Marathon, entering the big race before being forced to pull out (on doctor's orders) shortly before D-day.
A lesser woman might have hung up her running shoes. But Brand wasn't so easily defeated, and will this Sunday be competing in the Hydro Active Women's Challenge, a gruelling race around Hyde Park.
"She's doing the run for the Alzheimer's Society, and has been training, but not for the full 26 miles," reports Brand's agent. "It is, after all, holiday season and a time for sitting around and not doing very much."
In fact, the race is 5km long - but from such acorns do mighty oaks creep skywards.
* Following my revelation yesterday, the actor Samuel West has explained why - at the grand old age of 39 - he still requires financial handouts from his parents, Timothy West and Prunella Scales.
"You don't go into theatre for the money," he says. "And as artistic director of a regional theatre, your salary goes down a lot. Dad certainly used to help me out, though it's cheaper to live in Sheffield [where he's now based] than it was in London."
By way of a money-making scheme, West Jnr - speaking at the launch of the Gramophone Awards - is now writing a play about the World Snooker Championship, which is held at his current work place, the Crucible Theatre.
"We'll need to make sure that actors can play snooker before we hire them," he notes, sagely.
* Sir Alan Sugar's role in the recent Premium Bonds advert was unkindly labelled the most ludicrous acting debut in TV history.
It could soon lose its crown, though, becausee the cockney entrepreneur has just made a sequel advert for National Savings, this time endorsing its savings scheme.
Yesterday - oh joy! - I got hold of a copy of the script. It opens on: "Sir Alan Sugar walking around a futuristic space. Science fantasy images are projected."
"No one really knows what's gonna happen in the future," he says. "And I don't like surprises. That's why I do like inflation-beating savings... They're tax free, no risk. And I believe in 'em."
And does Sir Alan believe in 'em enough to dig into his own pocket? "Yes, but we can't say how much he's spent due to customer confidentiality," insists a spokesman.Reuse content