ES News email The latest headlines in your inbox twice a day Monday - Friday plus breaking news updates Enter your email address Continue Please enter an email address Email address is invalid Fill out this field Email address is invalid You already have an account. Please log in Register with your social account or click here to log in I would like to receive lunchtime headlines Monday - Friday plus breaking news alerts, by email Update newsletter preferences

Theresa May faced a sensational revolt today as local Conservatives backed Zac Goldsmith to stand as an independent anti-Heathrow candidate in a by-election.

In a bombshell development, the Tory group at Richmond Park held a private meeting last night where Mr Goldsmith confirmed he is ready to run as an independent if the Government backs a new runway at Heathrow.

In a secret ballot, the group voted overwhelmingly to support Mr Goldsmith rather than an official Conservative candidate.

Extraordinarily, Twickenham MP Tania Mathias took part and also vowed to support Mr Goldsmith — even though it is strictly against the party’s rules to back anyone standing against an official candidate. “They see it as a referendum via the ballot box on Heathrow,” said an insider.

Today the Prime Minister allowed Cabinet ministers to discuss the airports issue for the first time — though critics of Heathrow expansion, such as Boris Johnson and Justine Greening, were only invited to comment and not to vote.

The Government is widely expected to approve Heathrow’s long-running campaign to expand in a week’s time, a move that is bound to cause protests and face legal challenges.

Mr Goldsmith’s resignation as an MP will be triggered by a Government decision to back Heathrow — although local sources believe that he would wait until after a Commons debate before forcing the by-election.

The Liberal Democrats believe they could snatch victory in Richmond Park by running on an anti-runway platform, and Mrs May will now have to decide if she dares to field an official candidate against Mr Goldsmith.

It would be unprecedented for the party to avoid a by-election in a seat with a 23,000 majority, but she would risk splitting local Tories and being defeated if she imposes a candidate.

One Tory source dismissed the likelihood of a Lib-Dem win if Mr Goldsmith stood as an independent, saying: “He has a huge personal following.”

Sarah Olney, an accountant at the National Physical Laboratory in Teddington, has been selected as the Lib-Dem parliamentary candidate.

Dr Mathias said: “Zac is doing the honourable thing by committing to his pledge and I fully support him in that.” She vowed to fight a third runway in Parliament.

At Cabinet, Theresa May announced a temporary suspension of ministers’ collective responsibility on airport ex-pansion.

She said she recognised some ministers had long-held views and they would be allowed to set out their positions for a limited period. However, Cabinet collective responsibility would be applied to the final decision.

The unusual move aims to make it easier for Foreign Secretary Boris Johnson and Education Secretary Justine Greening, opponents of a third runway, to remain in Cabinet if the Government backs Heathrow expansion.

No 10 said that during the Cabinet’s talks on whether to expand Heathrow or Gatwick, a range of views were ex-pressed, confirming the deep divisions among ministers on the issue.

The final decision will be made by a Cabinet sub-committee next week.