Wednesday 30, 8.30am update: Farage has bottled it. As I wrote below yesterday evening, he’s a terrible tease about by-elections.

“A last word on Patrick Mercer: before entering Parliament, he served his country in the armed forces and was decorated for gallantry. Whatever he has or hasn’t done since, that should be remembered,” I wrote last May, when scandal engulfed the MP for Newark.  Now that he is no longer to hold that post, those are my first words this time round.  And I again make the point that Mercer is not an anti-semite.  Were he so, I don’t believe that he would have spoken of Jewish officers in the Sherwood Foresters, the regiment in which my uncle served and was wounded during the Second World War, with the respect and affection with which he has done in my hearing.  The Sherwood Foresters became the Worcestershire and Sherwood Foresters – Mercer’s own regiment.

That said, he should have resigned from the Commons as soon as the allegations were first aired. After all, the Newark MP accepts, in his euphemistic words, that he “got something wrong” and that “you have got to ‘fess up and get on with it”.  This was not in doubt from the first.  The whole business re-raises the proposal which Douglas Carswell and Zac Goldsmith have frequently championed, the latter recently on this site, of a right of recall by which constituents can depose sitting MPs.

Since Mercer has now announced that he will indeed stand down from Parliament, an important question is: when?  Government Whips were reportedly saying this evening that, even were he to apply for the Chiltern Hundreds immediately, the by-election could not take place on the same day as the European elections – because it is simply too late for that to happen.  But it is not clear whether this is really so.  Were the Newark MP to hang on for a few more days, however, it would certainly be the case.

Mercer and David Cameron are not exactly bosom buddies – the latter having sacked the former from his front bench amidst a contretemps about claimed racism.  Asked what the Prime Minister’s biggest mistake has been, the Newark MP has since been reported to have replied: “Being born”.  Perhaps to dispel any lingering ambiguity, he is said to have added that Cameron is “a most despicable creature without any redeeming features”, adding “I loathe him”.  This is why I described him as ” the man most likely to try to sneak the Claus Von Stauffenberg memorial briefcase into Number Ten”.

That briefcase didn’t kill its target – but it wounded him badly.  Mercer’s triggering of a by-election may have the same effect.  As I said, neither Cameron nor Miliband “can presume that UKIP wouldn’t win such a contest”.  Nigel Farage now claims to be mulling whether or not to stand, but the UKIP leader is a terrible tease on these matters.  (The Conservative candidate, Robert Jenrick, was recently the International Managing Director at Christie’s.  He also, for those who are interested in these things, “attended his local state primary school and Wolverhampton Grammar School.’)

What’s certain is that, whether Farage himself runs or not, UKIP are likely to have a second publicity bonanza after the European elections – which will test the nerves of Tory MPs.