If Boris Johnson does decide to precipitate an election this week he will be taking a considerable gamble. True, on average the polls now put him eight points ahead of Labour. With just 25 per cent of the vote there seems little prospect that an early ballot would catapult Jeremy Corbyn into Downing St.

However, Mr Johnson’s other opponents are in rather better health. At 19 per cent in the polls, the Liberal Democrats are in a much stronger position than two years ago. The Tories could well lose a good dozen seats to Jo Swinson’s party, and perhaps more if she can squeeze the Labour vote in some of the constituencies that her party held until 2015. Also riding high in the polls