After ten hours and sixteen votes, an agreement has been reached between supporters and opponents of Brexit in the House of Lords to pass Hilary Benn's bill to seek an extension to Article 50 by 5pm on Friday, which means that it is certain to become a law and a general election is on the way.

But when? The various opponents of a no-deal Brexit agree on the answer — as soon as their move to seek an extension has been legally confirmed. But they disagree about what that means: does it mean after the bill has become a law? That's the opinion of the leaders of both Labour and the Liberal Democrats — at least, that's what they both argued in the House.

The reason why passing the bill into law is important is that it guarantees that if the next parliament is hung, Boris Johnson cannot simply let the United Kingdom tumble out of the European Union before the new parliament meets. That, at least, is clear.

But some within their parties think that it means waiting until after Johnson has triggered the Article 50 extension, the better to humiliate him and deepen his problem with the Brexit party.

In practice, the debate is one over electoral strategy: what maximises the chances of producing a parliament that can prevent a no-deal Brexit again? I think both sides are at risk of being too clever by half.

The Conservative line that Jeremy Corbyn is scared of an election gives Johnson something to talk about other than his flawless record of four defeats in four in the House of Commons and seventeen defeats in seventeen in the House of Lords. The problem is that attacking someone for being too chicken to hold an election ceases to be a viable attack line once the election is underway. There's the risk, too, that the time simply gives Johnson longer to disintegrate on the campaign trail.

But the "let Johnson stew in his own juices" crowd are at risk of being too clever for their own good too. Holding off the start of the formal election campaign until after the extension has been triggered means effectively, a two-month election campaign on top of the 25 working day statutory campaign — but crucially, a two-month campaign in which the tighter broadcast rules around elections do not apply and there are no restrictions on what political parties and outside groups can spend.

That does mean that various pro-Remain and anti no-deal groups can organise and campaign to the heart's content: but more importantly it means that the full might of the government's advertising budget can also be deployed, while the government will continue to enjoy a disproportionate level of coverage for its announcements up until the contest proper starts. It also means two months of prominent headlines about Labour MPs and their trigger ballots.

Delaying also facilitates Nicola Sturgeon's attack line against Scottish Labour, that they are weak and indecisive and only a vote for her party is guaranteed to produce a Scottish parliamentary contingent capable of standing up to the Conservative government. (Though Labour may reason that they are going to get shellacked in Scotland come what may.)

Of course, an election runs the risk of a Johnson majority — but that's the risk of any election at any time. Neither big party looks certain to do best with an imminent election or by pushing it out to November: but to my eyes the risk of waiting is heavier for Labour.