And Britons were quick to pick up on the clues in the timing of the big news, with many saying surely the timing of the announcement was to suggest Carrie, 31, took advantage of the Leap Year to get down on one knee and pop the question to the Prime Minister, 55. In a statement released by No10 on Saturday the couple said their baby is due in early summer and revealed their plans to tie the knot – but did not give details on any dates.

Twitter users were quick to respond, with speculation about the exact nature of the Downing Street engagement spreading fast.

One person said: “Okay, I’m going to be the first to ask it.

“Given the date, did Carrie ask Boris?”

Another said: “So I wonder… did Carrie ask Boris to marry him today #justsaying #leapyearproposal.”

A woman with the Twitter handle @nicwil75 said: “I’m guessing Carrie Symonds used her leap year prerogative to propose to Boris”.

Independent councillor Andy Oddy of Euxton Parish Council sent a tweet to the Prime Minister asking for some clarity. 

He said: “@BorisJohnson can Carrie Symons confirm she did/did not do the proposing?

“It is a leap year 29 Feb.”

One person even predicted the big news as far back as December.

A Twitter with the handle @SusanJe23074261 said: “Boris had better beware – 2020 is a leap yer and Carried may have a plan.”

She accompanied the tweet with an emoji of an engagement ring.

Another person tweeting under the handle @tony_smith70 wrote: “I presume Carrie proposed to Boris today.” 

His views were backed up by others who said they had no doubt the former Tory aide was the one to get down on one knee. 

The person with the handle @MarthedeFerrer said: “I like to think Carrie made the most of the leap day and proposed to Boris Johnson.” 

A spokesman for the couple said: “The Prime Minister and Miss Symonds are very pleased to announce their engagement and that they are expecting a baby in the early summer.” 

More to follow….