Donald McIntyre: Is Vince in or out, flirting with Clegg or Ed?

Vince Cable has had the luck as a politician to see some of his enemies spontaneously combust. Bob Diamond. Rupert Murdoch. Er … Nick Clegg?

Perish the thought, of course. As the two men – so inseparable you wondered whether either was prepared to let the other out of his sight – toured the Ricardo hi-tech plant in Shoreham-by-Sea, Clegg seemed the chattier, Cable the more subdued.

We searched, largely in vain, for a twitch of mutually hostile body language. Asked, twice, about Boris Johnson's mischief-making call for the Lib Dem leader to be preserved for the nation, Clegg described the London Mayor as the "nation's greatest celebrity politician".

Could this have been a subtle dig at Vince – Boris's main rival for this dubious title?

Who can tell? Certainly Cable eschewed overt Borisian self-aggrandisement. Instead, his speech showed distinct signs of having it both ways. In the Government but not wholly of it. In particular, he indulged in a bout of only somewhat circumspect – and from the floor, well applauded – Tory-bashing.

His best and unscripted joke, "Not now, Ed", came as he seemed to reach for his mobile phone after an unrepentant reference to his SMS flirtation with the Labour leader.