This Saturday, a collection of approximately 25,000 private documents from Margaret Thatcher’s first year as Prime Minister (May – December 1979) was released for public viewing and consultation at the Churchill Archives Centre in Cambridge.

Among the documents are unexpected details of a protein-rich diet Thatcher took up only months before her 1979 election, and notes on Thatcher’s original choices for her first Cabinet, in addition to crucial texts relating to both foreign policy and domestic relations in the former British premier's first year.

A folded diet sheet found tucked inside Thatcher’s 1979 Economist pocket diary and entitled “Mayo Clinic Diet” outlines a nutritional regime designed to help its follower lose up to 20 lbs in two weeks.

The sheet bears Thatcher’s handwriting, including check-marks and “x”s next to each day’s recommended foods. The document suggests that Thatcher tried to lose weight at some point before the May 4 1979 general election, when she stopped using the diary.

The discovery of the diet sheet is especially interesting in light of a statement made by Thatcher in a Sun interview published in mid-March 1979. In the interview, she had said, “I have no special dieting regime of meals, I just try to eat little.”

“It's often best, you know: to do without completely. You can't indulge. It will sit on your hips,” she added. She also told her interviewer that she weighed 9 1/2 stone.

The “Mayo Clinic” diet recommends 28 eggs per week. Other foods on the political candidate’s diet included spinach, steak, cottage cheese and cold chicken. A note at the bottom warns that whisky is the only alcoholic beverage to be consumed, and that it can only be taken on days when meat is eaten.

Crucial documents in the wider collection include notes on the brainstorm behind Thatcher’s first Cabinet appointments. These show, for example, that Michael Heseltine, later instrumental in Thatcher’s fall from power, was originally intended to be Secretary of State for Energy, rather than Secretary of State for the Environment - the post he was ultimately given in 1979. They also reveal that Thatcher considered giving Nicholas Ridley a Cabinet post in 1979, but changed her mind, later appointing him Secretary of State for Transport in 1983.

Among thousands of other new documents are several files of congratulatory letters sent to Thatcher on her election as PM, including notes from American economist Milton Friedman, Road to Serfdom author Friedrich von Hayek, romance novelist Barbara Cartland, Telegraph Editor Bill Deedes (Denis Thatcher’s close friend, caricatured in the “Dear Bill” letters), and pop singer Lulu.

Even Lady Thatcher’s domestic tendencies are on display in some of the collection’s earliest documents, which include a hand-scrawled list of domestic arrangements (including a shampooing basin and arrangements for the storage of handbags and shoes) to be made for the Prime Ministerial flat in Downing Street.

The simultaneous opening, with this new collection, of parts of the collections of Thatcher Press Secretary Bernard Ingham and Policy Unit chief John Hoskyns, will allow for increased understanding of the behind-the-scenes work of Downing Street staff.

The papers released on Saturday under the 30-year rule complement the set of Thatcher’s official papers for 1979 which were opened last month in the National Archives at Kew. The opening of the two collections in such close succession marks “the first time that a British Prime Minister’s private and official papers have been released in tandem,” according to a Churchill Archives press release.

The Margaret Thatcher Foundation, in partnership with the Margaret Thatcher Archive Trust and the Churchill Archives Centre, also announced Saturday that it plans eventually to make all of Lady Thatcher’s papers, from the beginning of her career through 1990, available to the public for free through a digitization scheme. Those documents already released, in addition to photos and historical footage, can be viewed on the Margaret Thatcher Foundation’s website at www.margaretthatcher.org.

The Churchill Archives Centre, at Churchill College, houses Lady Thatcher’s private papers, along with those of Sir Winston Churchill and other notable twentieth-century politicians and scientists. The Archives are free and open to the public, and the newly-released Thatcher papers can be consulted on weekdays by appointment with the Archivist.