Boris Johnson intervenes in "Jones the Jag" row

For David Jones's political opponents, it's the gift that keeps on giving.

Today, the Mayor of London, Boris Johnson, intervened in typically mischievous style with a call to Deputy Prime Minister Nick Clegg's radio phone-in. He may have been trying to make a point about London transport funding, but asking Mr Clegg to "get all those government ministers out of their posh limos" won't have gone unnoticed at the Wales Office.

He signed off with the message: "Nick - get them out of their limos. Boris, over and out."

Mr Clegg said the government had cut the ministerial car bill inherited by the previous Labour government "I think by about 70%", which he described as "a big step in the right direction". (You may well wonder why the Wales Office didn't employ this argument when the "Jones the Jag" story broke rather than leaving it to the Lib Dem leader).

Mr Clegg said ministers didn't use cars all the time, adding that he was travelling to Sheffield later by train. Plaid Cymru leader Leanne Wood was asked about the issue during her guest-of-the-day appearance on the BBC's Daily Politics programme.

She said most people would have difficulty "understanding the rationale" behind the use of ministerial limos when so many voters were struggling to make ends meet.

But for the vagaries of the electoral, David Jones and Boris Johnson would be parliamentary neighbours ("I fought Clwyd South - and Clwyd South fought back") so perhaps Mr Jones shouldn't take Mr Johnson's intervention personally.

Labour's shadow Welsh Secretary, Owen Smith, endorsed the Tory mayor: "On this rare occasion, Boris Johnson is right... Jones the Jag should get out of his limo."

The Welsh Secretary himself, having seen his profile soar this week, has been trying to see the funny side of a story no-one (yet) is calling Jag-gate.

The writ for the Eastleigh by-election was moved this morning at Westminster and Mr Jones tweeted: "Looks like I'll be visiting Eastleigh a few times this month. Driving my own car."