In researching the first volume of the authorised biography of Margaret Thatcher, Charles Moore conducted extensive interviews with Lady Thatcher herself, her family, friends and former colleagues, many of whom had never before spoken on the record about her. But one of his most revealing discoveries was a cache of more than 150 letters written by Margaret to her sister Muriel, most between 1940 and the early 1950s. From them emerges not just the intense student with political ambitions, but a portrait of a passionate young woman who cared about clothes and – as the extracts reproduced here show – had sometimes complicated relationships with men that she chose never to mention in later life.