Boris Johnson and Marina Wheeler are to divorce after 25 years of marriage, the couple announced yesterday.

In a joint personal statement issued through a family friend, Mr Johnson and Ms Wheeler, both 54, said: "Several months ago, after 25 years of marriage, we decided it was in our best interests to separate.

"We have subsequently agreed to divorce and that process is under way. As friends we will continue to support our four children in the years ahead. We will not be commenting further".

The statement, which was sparked by an article in The Sun newspaper, comes a day after Mr Johnson was spotted deep in talks over lunch with Julian Smith, the Government’s chief whip, at a leading Westminster restaurant.

The news has emerged ahead of a pivotal 12 months for Mr Johnson, with the former Foreign secretary expected to challenge for the leadership of the Conservative party.

If Mr Johnson, Conservative MP for Uxbridge and South Ruislip, who writes a weekly column for The Daily Telegraph, succeeds Mrs May he would become the first divorced party leader to live in 10 Downing Street without a spouse.