Theresa May will not make a final decision on building a third runway at Heathrow for at least a year after announcing that she will give Boris Johnson and others the freedom to voice their opposition.

The Prime Minister told Cabinet colleagues that those with “strongly held views” would not be put in the “uncomfortable” decision on having to back the Government’s position if they do not agree with it.

She disclosed that the Government will announce its preferred choice for airport expansion at either Heathrow or Gatwick by the end of the month, but will not put the decision before Parliament until the “winter” of next year.

Her decision to give Cabinet ministers a “derogation” from collective responsibility, which requires them to support Government positions, will help her avoid high profile resignations.