Indeed, if Boris Johnson does the only thing he can feasibly do and resign, the big risk is that the Conservatives will tip back into civil war.

On 28 August 2019, the Houses of Parliament were ordered to be prorogued (suspended) from around 9/12 September to extend for five weeks. It was an attempt to prevent the 'no deal' option (for when the UK left the EU) becoming illegal via the the so-called 'Benn' Act; the deadline for agreement was then due at the end of October 2019. In R (Miller) v The Prime Minister and Cherry v Advocate General for Scotland, prorogation was ruled unlawful by the Supreme Court. See 2019 British prorogation controversy.