Everyone agrees that an election is coming in Britain, sooner rather than later. The outcome of parliamentary battles between Boris Johnson and his opponents will decide how and when that election is called. So far, the new prime minister has been coming off worse in those confrontations. But no matter what kind of mauling Johnson gets in the House of Commons, the most important job will still have to be done.

What are the electoral prospects for Jeremy Corbyn’s Labour Party, if and when this parliament is dissolved? The most recent opinion polls don’t look promising for Labour, but the same point could have been made in 2017, with even greater force. Can Labour match its surprising result two years ago, which set the scene for the current Tory crisis — or even go one better?

The 2017 UK general election is the closest benchmark we have for what’s going to happen next. Layers of mythology have already piled up around that election: peeling them back will help clarify whether it’s likely to be repeated.