Mr Major is back where he started in January, but with an even narrower parliamentary majority and less time to overturn a huge opinion poll deficit.
After a six-month truce over Europe, Conservative Euro-sceptics rebelled before Christmas to inflict a defeat on the Government over European fishing policies. Now a second centre-left MP has defected to an opposition party.
And more feel the same way. One prominent backbencher said he had been shocked to realise that "the policies the nation needs were better expressed by Labour than the Conservatives".
Asked if he would consider following Miss Nicholson across the floor of the house, he said: "I have thought about it; it is only social reasons which are keeping me in the party, really. The main thing is that I couldn't kick my constituency workers in the teeth after they have seen me through thick and thin." He warned that the loyalty of left-leaning Conservatives could not be taken for granted while Mr Major "pandered to the right".
Another said: "John Major should realise that the right has nowhere else to go. The centre-left have somewhere else to go, and so too do the vast majority of the British electorate."
He condemned the Government for "appealing to base prejudice and the idiot, insolent and arrogant right" and attacked Michael Howard's "odious" attitude to prisons.
Last week Hugh Dykes, the Harrow East Tory MP, signalled growing left- wing Conservative dissatisfaction when he said that Mr Major had "caved in" to the Euro-rebels.
Jim Lester, the MP for Broxtowe and one of the few left-leaning Conservatives prepared to go on the record yesterday, said that while he had no problems with Mr Major's leadership, the Government could not count on him supporting Mr Howard's Asylum Bill.
But while this growing dissatisfaction on the left and right of the party saps Government authority, it will not necessarily trigger a general election in 1996.
Mr Major's majority now stands at five. Assuming he loses the two by- elections in Staffordshire South-east and Hemsworth, Yorkshire, that falls to three, or one after MissNicholson's defection.
However, the Conservatives are still the largest single party and Unionist sources say that, unless a new factor enters the equation, they will not seek to bring the Government down. Conservative whips expect that, if a vote of confidence is called, the Unionists will abstain, allowing Mr Major to scrape through with a majority of up to 10. Labour argues that, because many MPs from minority parties have poor attendance records, Mr Major's working majority is in the "upper teens". In 1978-79 Labour survived with much worse parliamentary arithmetic. However, it went on to lose the next election.Reuse content