With several Cabinet ministers - led by David Hunt, the Secretary of State for Employment - being canvassed as his successor, Sir Norman accompanied his announcement with an appeal for unity and a pointed attack on party divisions in the 18 months before the European elections.
Sir Norman, skilfully stole some of the television publicity from Labour's leadership contest in his last important act as chairman.
He made it clear last night that he was remaining an MP and would adopt an aggressively loyalist role on the backbenches. He is known to have been exasperated by the public divisions during the local election campaign - especially the eve-of-poll call by David Evans, the outspoken MP for Welwyn and Hatfield, for Mr Major to dismiss sack several prominent members of the Cabinet.
His departure had been widely trailed, and Sir Norman took the decision to go six months ago.
Senior Tories insisted last night that no decision had been taken on his successor, and some are urging Mr Major to confront Michael Heseltine, President of the Board of Trade, with an offer of the post. Mr Heseltine does not want it, but pressure could mount on him over the next fortnight. And some Tory right wingers suspicious of the Employment Secretary's pro- Europeanism, oppose Mr Hunt's candidacy. Other possible names - in a long series - include Gillian Shephard, Virgina Botmley - and outside the Cabinet Jeremy Hanley, a defence minister and Brian Mawhinney, Minister of State for Health.
Mr Major has privately indicated that Ian Lang, the Secretary of State for Scotland, would make an excellent chairman and he has the primary qualification of being close to the Prime Minister. But with his constituency, Galloway and Upper Nithsdale, being distant from London, he would have an even worse problem than Sir Norman's predecessor Chris Patten in nursing a marginal seat. Tony Newton, leader of the Commons, is also close to Mr Major but there are doubts whether he has the right brand of politicial pugnaciousness for the job.
Sir Norman said his job - which had involved a big shake-up of Central Office and finances - was 'now complete'. The party made a pounds 2m operating surplus in 1993-4, its first for several years.
In a frank - and characteristically robust - assessment of his own qualities, Kenneth Clarke, the Chancellor and still a strong contender to succeed Mr Major, says in a BBC interview to be broadcast next Sunday: 'I don't think you can go into politics if you have significant doubts about your own capacity. . . Anyone nagged by those self-doubts should find another way of earning a living.'