“These are serious allegations of possible breaches of the Ministerial Code by Theresa Villiers when she was Transport Minister.

"The PM should urgently confirm that the Cabinet Secretary is investigating these breaches and that the findings of these investigations should be made public.

"The allegations also involve representations made by a Conservative councillor in the PM’s constituency. Therefore, in the interest of transparency the PM should refer the allegations to the Independent Advisor on the Ministerial Code.”