Theresa May accidentally burst in on a couple having sex while canvassing during last year's ill-fated general election campaign.

The Prime Minister said in a speech to political journalists and senior ministers that it gave a "whole new meaning to the phrase ‘deep and special partnership".

Mrs May revealed a gift for self-deprecation and incisive jokes about herself, her Cabinet and journalists in a speech to the Westminster Correspondents' dinner.

Mrs May told 250 guests at the dinner including Chancellor Philip Hammond and Home secretary Amber Rudd that one canvassing trip "in particular sticks in the memory”.

She said: “I was at the open door of a caravan and there was clearly some activity within, so I duly knocked. No answer — but the activity persisted.

"It looked like there was someone lying down. I knocked again, and put my head around the door. There was someone lying down … In fact, two people were lying down.

"And it wasn’t a good time to ask them if they were going to vote Conservative … They were giving a whole new meaning to the phrase ‘deep and special partnership.’”

The Prime Minister added: “I’m used to hearing moans on the doorstep, but this was something else.”