BORIS Johnson is poised to miss a crunch vote on Heathrow expansion – after Number 10 decided on a showdown next Monday.

Sources claimed Downing Street will put a third runway to MPs on June 25.

Boris Johnson is poised to miss a crunch vote on Heathrow expansion on Monday night Credit: Reuters

The Foreign Secretary and fierce opponent on a third runway is due at a meeting of the EU Foreign Affairs Council in Luxembourg that day.

It means he would able to avoid voting against the PM – and a "three-line whip" slapped on Tory MPs by the Government.

The Sun last month revealed Mr Johnson had told colleagues he would duck a vote by heading overseas.

The Foreign Secretary famously called for a new airport to be built in the Thames Estuary – and said he would “lie down in front of bulldozers” to stop a third runway at Heathrow.

Foreign Secretary and fierce opponent on a third runway is due at a meeting of the EU Foreign Affairs Council in Luxembourg that day Credit: PA

Theresa May is almost certain to win next week’s vote with Jeremy Corbyn set to allow Labour MPs a “free vote” on the issue.

Labour MPs are understood to have met earlier today to discuss the issue.

Transport Secretary Chris Grayling earlier this month urged MPs to back Heathrow expansion – saying: “The time for action is now.”

A spokesman for Boris Johnson declined to comment today.