Lady Thatcher and Sir Edward became bitter rivals after she ousted him as Conservative leader in 1975.

Sir Edward Heath: Self-confessed sulker

From the backbenches of the House of Commons, he kept up a highly critical commentary on her premiership, which started four years later. From 10 Downing Street, she dubbed him a "wet".

The UK's first women prime minister chose a Park Lane reception to celebrate the 20th anniversary of her election to hold out an olive branch to her former foe.

But some observers afterwards pointed out the odd thorn still lurking along the stem.

The BBC's Carole Walker: "Something of a reconciliation"

In her address to 1,000 of the Tory faithful, Lady Thatcher said: "I would like to take this opportunity publicly to pay tribute to Ted as one of the Britain's most forceful and effective prime ministers.

"Go back and read his 1970 manifesto. It is one of the boldest and best the Conservative Party ever produced - a document not for burning."

Sir Edward described himself as "delighted" at the tribute, but declined to reciprocated it in kind.

Side-by-side: Sir Edward stays on Baroness Thatcher's left

Friends of Lady Thatcher later drew attention to the careful phrasing of her remarks. Her split with Sir Edward resulted from his abandonment of his manifesto promises, they said. While she may have approved of his "forceful" style, his policies in government remained an anathema.

The former prime ministers went on to share a joke on the podium. Lining up to have their pictures taken, Lady Thatcher suggested Sir Edward should stand on her right. "That would be difficult," he quipped.

The attempt at healing old Tory wounds came on the night the new breed of Conservative leaders try to chart a course for the party away from the "if it moves, privatise it" image.

William Hague was careful to pay his own homage to Lady Thatcher while backing his deputy Peter Lilley, who is stressing the Tories' commitment to public funding for health and education.

Despite this, many will view the shift in policy as a climbdown from the Thatcherite monetarist pinnacle back towards the centrist ground occupied by Sir Edward.

The former prime minister has admitted his behaviour following his defeat as party leader amounted to the longest sulk in political history.