Boris says that if he had resigned over Heathrow it would have achieved nothing.
I disagree. Here is why the Foreign Secretary should have resigned.
1) Boris is/was right about Heathrow, so he might as well own the vindication. The airport is in the wrong place, which means flying planes over the middle of one of the world’s key cities. Something will go wrong one day and then there will be remorse and a realisation that like the Gulf States, and Hong Kong, and Japan, we need to create a new airport properly. Even if you add a third runway it can never be what the UK needs to compete, that is a four or five runway airport (short of demolishing Windsor Castle.) That argument looks lost, for now. It may come back when people realise that the owners of Heathrow have greedily sucked all the value out, piling on debt, leaving the tax payer to stump up for an over-priced plan. The government of which Boris is a part is making an expensive and daft mistake. Say so, and resign. Be right.
2) A resignation would have been a moment of national healing, because Boris resigning would have cheered almost everyone up. Angry remainers and Brexiteers unhappy with the way he has performed as Foreign Secretary would have been given something they can agree on. A glimmer of light suggesting future peace post-Brexit.
3) A resignation might have been the trigger for a Tory leadership race or a cabinet coup. Britain is trying to Brexit without a functioning Prime Minister. It has a leader who cannot make decisions. Someone needs to break the jam. Someone needs to call time. Boris probably wouldn’t win such a contest or a coup now, but he could do the nation a service.
4) Boris has a particular view of Brexit. The government is going in another direction, towards an atrocious deal. May doesn’t listen to him. Better to be outside and make the case while there is still time, in a bid to reset the talks.
5) Boris had a contract to write a ripping yarns-style biography of Shakespeare. The project was shelved in 2016, to the glee of professional Shakespeareans in academia who could not wait to find fault and trash it. From the backbenches Boris could revive it, sell loads of books and in the process further infuriate all the luvvies most angry with him for Brexit.