As the search for their fourth leader in five years gathered pace, the Conservatives last night broke off from scheming behind the scenes to seek solace in the memory of past glories when they gathered to celebrate Baroness Thatcher's 80th birthday.

The Queen and Tony Blair were among 670 people invited to a lavish reception in central London where the guest list included scores of disciples of the "Iron Lady" as well as a smattering of foes.