The Prime Minister Boris Johnson and his girlfriend Carrie Symonds are expecting their first child and have announced their engagement.

The couple said their child would be born in the early summer and revealed they got engaged at the end of last year.

A spokesperson for the couple made an official announcement this afternoon, saying: "The Prime Minister and Ms Symonds are very pleased to announce their engagement and that they are expecting a baby in the early summer."

Ms Symonds, 31, then posted a message on Instagram admitting she had kept the news of her engagement secret until now, saying: “I wouldn’t normally post this kind of thing on here but I wanted my friends to find out from me.

“Many of you already know, but for my friends that still don’t, we got engaged at the end of last year . . . and we’ve got a baby hatching early summer. Feel incredibly blessed.”

The couple enjoyed a luxury Caribbean vacation in Mustique at the end of December last year.

The announcement of their forthcoming wedding means Mr Johnson will become the first Prime Minister to marry in office for nearly 200 years.

Mr Johnson and Marina Wheeler, a barrister, reached a divorce settlement in February.