Archived papers reveal Thatcher secrets
The Conservative party came close to splitting in 1981, newly released papers from the Margaret Thatcher Archive Trust show.
Many doubting ministers had been sacked in a September cabinet reshuffle, the so-called "purge of the Wets".
But in November 1981 Mrs Thatcher faced a rebellion of backbench MPs too.
The government's monetarist policy in the autumn was controversial and the papers show even some senior party figures did not understand it.
It certainly did not seem to be working. Factories were closing across the country, unemployment rising fast, and inflation was growing too.
And so on 25 November, the Chief Whip received a letter from 25 MPs, saying they would not support the government's economic policy if the effect was to "deflate aggregate demand".
The group of rebels was quickly named the Gang of 25 by the prime minister and her circle, echoing the "Gang of Four" nickname given to the founders of the Social Democratic Party (SDP). Many of the signatories were talented young MPs, like Stephen Dorrell.
Their number grew swiftly. In early December the Chief Whip, Michael Jopling, warned as many as 45 MPs might vote against the government - the conservative majority was only 45.
The main risk was not that the government would be defeated - but that these MPs might defect to the SDP.
The new Social Democratic Party had been created in March that year, by four senior, centrist Labour politicians who had formed an alliance with the Liberals.
In late summer, disturbingly for the party, private polling by the Conservatives suggested this alliance might get as many as 40% of the votes in an election - against 16% for the Conservatives. This was far worse than the published polls.
Then, in November, Shirley Williams won a stunning victory at the Crosby by-election, replacing what looked like a safe Conservative majority of 19,000, with a respectable 5,000 majority of her own.
A research paper sent to Mrs Thatcher afterwards warned that while the alliance might bury the Labour party, it also threatened to "sweep the Conservative Party into a small minority position, worse than anything we have experienced for over one hundred years".
One Conservative MP had already defected, and Mrs Thatcher was advised there was a real risk more might follow.
Roy Jenkins, one of the Gang of Four, admitted in his memoirs that the party had been courting Conservatives, keen to show they were a new party of the centre. The private papers show the Conservatives were particularly worried about Stephen Dorrell.
The Whips worked to split the rebels. Stephen Dorrell, and Chris Patten, another of the Gang of 25 were invited for drinks at Number 10, along with a couple of loyalists.
The rebellion fizzled out. When a key vote was held on 8 December, only 14 MPs abstained. But it was an indication of how difficult the prime minister's position was.
In December 1981, Mrs Thatcher's closest political ally, Ian Gow, wrote her an emotional private letter - putting on paper, he said, things she would never let him say to her face.
Ian Gow was Parliamentary private secretary to the prime minister and eventually given his own portfolio as minister of housing. Later an opponent of the Anglo-Irish Agreement, he was assassinated by the IRA in 1990.
He called her a "giant among pygmies", and said she was "fighting a battle as heroic as any we have fought in the past".
He praised her vision, determination, and talent - but he said he did not know whether her "iron resolve" would be "sufficient".
There was what the Thatcher Foundation historian Chris Collins terms as "a feeling of the bunker" in Number 10 as the year ended.
Elsewhere in the files is a box of letters Mrs Thatcher kept - a few score out of the thousands she received.
One, from October 1981, is from a survivor of the Titanic, WR Richards, who'd been saved a toddler in 1912. He had seen a cartoon in the Daily Express depicting Mrs Thatcher as an iceberg, about to hole the "SS Strike".
"As a survivor of the Titanic" he wrote, "I hope that you too will be a survivor. Good luck to you and all your crew!"