Nigel Farage's demand for a second referendum if Remain wins has met with the same reaction with which the famous heckler at the Glasgow Empire greeted Mike and Bernie Winters: "Och, Christ. There's two of 'em.*" In fact, though, it has a serious implication - it means undecided voters should vote Remain.

The reason for this is simple. If Mr Farage gets his way then if you vote Remain and regret it, you'll have a chance to change your decision. If, however, you vote Leave and regret it, you'll have to live with your regret; nobody is proposing a re-match in this case.

If you regard both possibilities as equally likely - as I guess many undecideds do - then voting Remain is obviously the thing to do. It gives you a chance to change your mind whereas voting Leave does not.

To put this another way, if you vote Remain you retain an option to leave. But if you vote Leave, you have no such option: your choice is irreversible. Common sense - and real options theory if you want to be fancy - thus says that undecideds should vote Remain. Remain plus an option to leave is, for anyone roughly undecided, a better choice that Leave with no option.

For me, this is one of the strongest arguments for Remain that I've heard. (It's so powerful that it should lead to such a strong Remain vote that even Mr Farage won't demand a re-match, but let's leave aside this paradox.) The fact that it comes from an ardent Leaver only confirms my prior, that the Brexit debate is characterized by a lot of counter-advocacy.

* Other accounts have a more realistic description of Glaswegian argot and the Winters' talents.