Dictators sometimes miscalculate. So I suppose it is possible that Robert Mugabe – failing to realise the depth of his own unpopularity – has just gone down to an electoral defeat in Zimbabwe that is so catastrophic that even he will be unable to reverse the result. But I am pessimistic. Mr Mugabe does not strike me as somebody who is likely to be shamed into doing the right thing. Nor is he the kind of man, who is likely to shrug and say that retirement might not be such a bad option after all. Maybe the army will turn against him? Otherwise, I think he will just dig in his heels and declare victory.

So what happens if Mugabe has indeed been clearly defeated – but decides to cling on to power and to brazen it out? I’ve just been listening to Lord Malloch Brown, Britain’s Africa minister, talking on the BBC World Service. He unequivocally ruled out the possibility of military intervention. Instead, he suggested two courses of action. First, Britain and other western countries should be absolutely clear in condemning a rigged election. Second, we should support African-led attempts at mediation – modelled on Kofi Annan’s efforts in Kenya.

Well, that sounds fine as far as it goes. But those measures don’t sound strong enough to dislodge a determined dictator like Mugabe. (And there is a big question mark – anyway – over whether Zimbabwe’s African neighbours, in particular South Africa, will be willing to get involved. Their record so far is pretty feeble.)

So if the kind of measures that Malloch Brown suggests won’t work, has anybody got any better ideas? What could the outside world do to support democratic change in Zimbabwe?

And – best case scenario – let’s say Mugabe is prevailed upon to step aside, what then? Some of his most damaging economic changes – in particular, the destruction of the farming sector through land redistribution – may be irreversible. So how could the outside world help a new Zimbabwean government?