SO DAVE plans to legislate to force MPs and peers to prove they’re UK tax-payers or lose their seats.

You would have to be certifiably and terminably bewildered to fall for that, surely? Zac Goldfinger admits to being a “non dom”, says he plans to continue that status right up until the election (because he’s not breaking any rules, right?) then does a U-turn and – inexplicably (because he wasn’t breaking any rules, was he?) – announces he’s giving up his non-dom status with immediate effect.

And then there’s Lord Ashcroft.

All very embarrassing for Dave. So how to recover lost ground? Easy: pretend that he’s going to be tough on his rich friends. But he can only do it once he’s Prime Minister, you see, so the only way to bring these greedy, disreputable Tories to book is to… er, elect a Tory government. Genius!

Well, he may not be Prime Minister but Dave does have authority (it is claimed) within his own party. So why doesn’t he tell Lord Ashcroft to appear on the Today programme this week and announce, once and for all, whether or not he is resident in the UK for tax purposes – the condition, after all, on which his peerage was bestowed?

If this doesn’t happen we can draw one or both of two conclusions: either Dave doesn’t have any authority at all over his Lordship, and/or his Lordship does, indeed have something to hide.

Cameron doesn’t need a new law to force Ashcroft to come clean – he can force him, if he chooses. He can sack him from his job as the Tories’ deputy chairman. A failure to do so (or to force him publicly to clarify his tax status) will prove he hasn’t the backbone to run his own party, let alone the country.