Thatcher declared war on youth culture at the end of the 1980s Poll Tax protestersCredit: HULTON ARCHIVE She launched a private battle against the European Commission after it announced it was repealing the Sex Discrimination Act, removing protection for Oxbridge colleges.Mrs Thatcher, who had studied at Somerville, said: “To stop [the existing policy] would infringe not enlarge liberties.”The Prime Minister would resist the move “most vigorously”.Plot to destroy cocaine crops by spraying bugsSecret plans to sabotage cocaine production abroad by introducing plant-destroying pests were put forward as the Government waged war on drugs.Thatcher described the idea, which was proposed by Lord (Victor) Rothschild in July 1989, as a “characteristically brilliant” and “intriguing” way of tackling the growing “crack problem”.Lord Rothschild suggested using “covert” tactics and aerial sprays to introduce a bug which would attack the source of cocaine, Cabinet Office papers released by the National Archives show. Downing St residents risked poll tax fineMrs Thatcher was warned she faced a fine for failing to register for the poll tax on time.The embarrassing oversight was quickly rectified, but it marked an inauspicious start for a measure that prompted a storm of protest and may ultimately have led to her downfall.In early 1989, as the political storm around the levy was gathering strength, Westminster city council began issuing registration forms ahead of the launch of the tax in England and Wales in April the following year. She also light-heartedly complained about a recent debate she had attended in Cambridge, which was “rather dull” and full of “rabid conservatives”.“Not a Trotskyite to argue with!” she quipped.The pair also discussed the first national steel strike in 50 years, which took place in January 1980 following a dispute over pay, while the Princess admitted she was finding it “quite impossible to find out what is happening in Afghanistan”.The Prime Minister, meanwhile, expressed her dismay at the ongoing hostage crisis at the US embassy in Iran, complaining that events had “cast a shadow over the whole world”.A spokesman for Buckingham Palace did not comment on the letters but a palace official said they were “comfortable” with the release.It came as other documents showed Mrs Thatcher attempted to block a visit to Brussels by the Queen and Duke of Edinburgh over fears it would come at a “very bad time” for policy negotiations in Europe. The Prime Minister expressed concerns that plans for the royals to visit the European Commission and meet the King of the Belgians in 1980 would clash with a settlement on fishing policy. No 10 stressed Mrs Thatcher’s concern, but the Queen went on to visit Belgium in November of that year. Princess Margaret with Denis and Mrs Thatcher In the 1980sCredit:Getty Images Margaret Thatcher as she raises her glass at Somerville College, her old Oxford CollegeCredit:PA Wire Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. Mrs Thatcher hated acid houseAcid house parties became a personal crusade by Margaret Thatcher after she received a complaint from a villager about the noisy all-night raves.The Prime Minister urged the Government to combat the “new fashion” and “prevent such things from starting”. Huge unlicensed parties were held across Britain between 1988 and 1989 as the dance music movement spread, earning the period the nickname “the Second Summer of Love”. Officials arranged for the prime minister to complete the form, only to discover that the council had sent the wrong one and she had to do it again.Mrs Thatcher responded cheerfully enough, noting her first effort had been “a good practice run”. The tax, officially known as the community charge, was a flat rate levy on all residents on a property and was widely seen as unfair to the poor.Other documents show that officials worried that a decision to allow MPs to claim the poll tax on their second homes through expenses could allow the press and opposition to “make a considerable amount of mischief”. In what Mr Powell described as an “unusually warm and friendly” letter, the Russian – addressing her for the first time in their correspondence as “Margaret” – expressed his appreciation for the “mutual understanding” they had established.In other documents, the anger of her closest aides was disclosed. Mr Powell, especially, could not hide his own views. Responding to a message from Brent Scowcroft, the US national security adviser, he said: “What happened was a devastating blow and a sad commentary on standards of loyalty in politics.”Battle to keep male dons out of collegesThe idea of forcing women-only Oxbridge colleges to hire male dons was “absurd”, Mrs Thatcher argued. The private events were held illegally and often included drug taking.Officials warned that any proposed legislation should not affect those attending “innocent events” such as barn dances, papers released by The National Archives show. Nigel Lawson in 1986Credit:Rex At the time, Mrs Thatcher insisted the £14 million a year they were spending on milk would be better spent on new school buildings.But when Kenneth Clarke wrote to her in May 1989 to suggest ending free milk for children in daycare, she replied: “No. This will cause a terrible row – all for £4 million. I know – I went through it 19 years ago.”Thatcher’s one-woman crusade against litter loutsParking wardens were to be given power to fine litter louts, under plans considered by Mrs Thatcher as part of an attempt to clean up Britain in the Eighties.Documents reveal that she virtually single-handedly drove the campaign by encouraging a variety of ideas in Whitehall. Margaret Thatcher at 10 Downing Street during general election, London, Britain – 1983Credit:Rex Features/Herbie Knott Legislation to tackle the dance movement was introduced by the Entertainments (Increased Penalties) Act 1990, also referred to as the Acid House Bill, which heightened punishments for those organising parties without licences which played ‘repetetive beats’.Mrs T was a secret pal of Princess MargaretShe was reported to have a chilly relationship with the Queen, with some reports going so far as to claim the monarch mocked her accent and could not bare the way she “lectured”.But Margaret Thatcher seemingly enjoyed a secret friendship with the Queen’s sister. In fact, the Prime Minister and Princess Margaret were so friendly they discussed the royal’s recent operation alongside world issues in a series of intimate letters, it has now been revealed. Extent of economic adviser’s briefing against LawsonNigel Lawson resigned amid bitter feuding as advisers battled behind his back to have him removed.The Chancellor of the Exchequer’s decision to quit in October 1989 came as a heavy blow to Margaret Thatcher and helped to precipitate the events which led to her downfall.His walkout was prompted by her refusal to sack her economics adviser, Prof Sir Alan Walters, whom Lawson accused of undermining his position. But files have revealed the extent to which Sir Alan briefed against him. Princess Margaret in 1991Credit:RICHARD YOUNG/REX/Shutterstock The handwritten notes, sent between the Prime Minister and Princess Margaret at the beginning of 1980, were laden with compliments as the pair discussed topical issues, from Afghanistan to the steel industry.The rare release shows Mrs Thatcher praising the royal for her “wonderfully successful” tour of the United States, as she revealed she was “very distressed” to hear she had been admitted to hospital again.“You very kindly wrote to me after your own visit to the United States, which was wonderfully successful both in the admiration you won and in the financial results for Covent Garden,” she wrote in the letter, sent at the beginning of January that year. “Incidentally I went to Covent Garden on New Year’s Eve and Claus Moser [the former chair of the Royal Opera House] was still talking of your tour.” In the candid note, the Prime Minister also confides in the royal about how nervous she is to “take the chair at Neddy” – the National Economic Development Council – for the first time.“[It is] hardly the best moment but we were never to know that when the meeting was fixed,” she confessed.Around four weeks later, at the beginning of February, the Princess replied, apologising for the delay and explaining she had “just had to have some things dug out of my face”. She had actually just had an operation at the London Clinic to remove a benign skin lesion. In the letter, signed “Margaret”, she praised the Prime Minister for her trip to the United States, expressing delight that she had surprised them “no end at answering their questions in a positive way, when they are used to waffling on for hours in figures of eight, not actually answering anything”. Margaret Thatcher goes litter picking in St James’s Park Credit:PA Margaret Thatcher at the Conservative Party Conference in Blackpool, October 1987Credit:Fox Photos/Hulton Archive/Getty Images One proposal, mooted in November 1987, was for traffic wardens to be given powers to levy on-the-spot fines if people were spotted dropping litter.The idea was rebuffed, with the reply that wardens were ‘hard-pressed’ enforcing road and traffic law.World leaders’ disbelief at Thatcher’s oustingWhen the news broke that Margaret Thatcher had been ousted by Tory plotters after 11 years in office, world leaders and allies were left in disbelief. Documents lay bare their shock and show a remarkable outpouring of commiserations from those who had come into contact with her.Among the first to respond was Henry Kissinger, the former US secretary of state who telephoned Charles Powell, her foreign affairs adviser, in a “very emotional state”.In a note to Mrs Thatcher, Mr Powell said the American had told him that her departure “was worse than a death in the family”.The most remarkable message came, however, from Moscow and Mikhail Gorbachev, the reformist Soviet leader whom Mrs Thatcher had described a man to “do business with”. Margaret Thatcher and Mikhail Gorbachev in 1984Credit: Sipa Press / Rex Features A form covering the various residencies in and around Downing Street was sent to the Treasury. But the Cabinet Office complained that it was “most inappropriate” to issue a single form “asking a number of essentially personal questions”. Individual forms were dispatched, but there were still no details forthcoming. In May 1989 David J Hopkins, the council registration officer, sent a letter addressed to the “Resident/Owner” at No 10 Downing Street warning: “You are required by law to supply the relevant information within 21 days of this request and failure to do so may lead to a penalty being imposed.” In a memorandum to the prime minister dated October 4, 1989, he warned that the Chancellor’s policy of “shadowing” the German mark – Europe’s strongest currency – with sterling was having a devastating impact. The high interest rates needed to maintain the value of the pound risked tipping the economy into a “serious recession”, he said. “The pattern of events, like a Greek tragedy, is painfully familiar” he wrote. A week later he warned that the policy was playing into the hands of the Labour Party and could cost her the next general election.“This sorry process, loaded in favour of their financially irresponsible policy, must not be allowed to gather force and votes,” he said.When Mr Lawson announced on October 6 that he had had enough, Mrs Thatcher pleaded with him to stay. However her close advisers suggested she was well rid of him.Andrew Turnbull, her private secretary, said the true reason was her rejection of a demand by Mr Lawson and foreign secretary Sir Geoffrey Howe for Britain to join the European exchange rate mechanism (ERM).He accused the Chancellor of shadowing the mark as an attempt to enter the ERM “by the backdoor”.’Milk snatcher’ barb still stung 19 years laterThatcher “the milk snatcher” was so haunted by criticism for axing free school milk when she was education minister in 1970 that she refused a similar cut nearly 20 years later over fears of more outrage.