Writing of his former Cabinet colleague, Lord Tebbit said: "At times his conduct has been tasteless, tacky if not dishonourable, and self-centred beyond even the call of his profession."
In a review of Michael Crick's new biography of the Deputy Prime Minister, he wrote in the Spectator: "The only thing for which Heseltine will be remembered, [is] the political regicide which brought down our greatest post-war prime minister."
He said that as an adolescent, Mr Heseltine turned himself into a political missile, targeted on the office of Prime Minister. "Like a laser-guided weapon, once assigned to his mission, Heseltine has remained on track ever since."
But Lord Tebbit took evident satisfaction from his conclusion, that the missile's chances of hitting its target - Number 10 - were fast receding. "It is still on track but running out of fuel," he said, "and the target is accelerating away".
As for the book's judgement, Lord Tebbit said: "Heseltine appears as a man of no great political insight, but a shrewd political operator, driven by ambition rather than idealism. Neither particularly left or right, a corporatist and fixer by instinct and practice, he could never understand Margaret Thatcher."
But he also alleged that there was an inbuilt male-chauvinism at work, saying: "At the roots of his hostility to her is a macho streak which sees only a subservient role for women, however talented, and a resentment that a woman achieved the supreme office which he coveted and which was denied him."
Balancing an essentially hostile verdict on the Deputy Prime Minister, Lord Tebbit said that in spite of bungled privatisations of the Post Office and coal, it would be wrong to forget Mr Heseltine's successes. "His establishment of the Audit Commission, the creation of the Urban Development Corporations and his successful campaign against CND [Campaign for Nuclear Disarmament] weigh heavily in his favour."
But his overall verdict is negative. "Heseltine's laser-guided system can focus on only one target at a time," he said. "He is a supremely good one-ball juggler, but a prime minister must keep a dozen or more balls in the air - and that he could not do."
The Tory bile later spilt over to the left of the party when Sir Nicholas Scott, a former minister, defended Mr Heseltine, saying Lord Tebbit had "gone over the top" and that he was longer regarded as "a serious player in the political field".
As for Lord Tebbit's charge of dishonourable conduct in pursuit of the leadership, Sir Nicholas told Radio 4's The World at One: "I don't believe he has pursued that ambition in any sort of underhand way. He has been open. He has been articulate."