Diana Mitford, the daughter of the 2nd Baron Redesdale, was born on 10th June, 1910. The sister of Unity Mitford, Nancy Mitford and Jessica Mitford, she was educated at home (Astall Manor) by her mother.
In 1929 Diana married Bryan Guinness, the heir to the brewing fortune. The couple had two children, Jonathan and Desmond.
Diana's parents held right-wing political views and supported the British Union of Fascists and in 1932 she was introduced to its leader, Oswald Mosley. Diana immediately fell in love with Mosley and later claimed that she knew the relationship "would never end except with death". Diana left her husband but Mosley refused to desert his wife, Cynthia Curzon, the daughter of the former Viceroy of India. It was not until Cynthia died of peritonitis, that Mosley agreed to marry Diana.
Diana and her sister, Unity Mitford, were regular visitors to went to Nazi Germany. While there they met Adolf Hitler, Heinrich Himmler, Herman Goering, Joseph Goebbels and other leaders of the Nazi Party. Hitler told newspapers in Germany that Unity was "a perfect specimen of Aryan womanhood".
In October 1936, Diana and Oswald Mosley were secretly married in Nazi propaganda minister Joseph Goebbels's drawing room in Berlin. Adolf Hitler was one of only six guests at the ceremony. While in Nazi Germany Diana talked to Hitler about the possibility of establishing a pro-Nazi radio station in Britain. In 1938 Diana was told there were plans to build a transmitter on a North Sea island. However, the project was abandoned on the outbreak of the Second World War.
On 22nd May 1940 the British government announced the imposition of Defence Regulation 18B. This legislation gave the Home Secretary the right to imprison without trial anybody he believed likely to "endanger the safety of the realm". The following day, Diana and her husband Oswald Mosley were arrested. Over the next few days other prominent figures in the BUF were also imprisoned. On the 30th May the BUF was dissolved and its publications were banned.
Diana and her husband received privileged treatment while in prison. Winston Churchill granted permission for the couple to live in a small house inside Holloway Prison. They were given a small garden where they could sunbathe and grow their own vegetables. They were even allowed to employ fellow prisoners as servants.
In November 1943, Herbert Morrison controversially decided to order the Mosleys to be released from prison. There were large-scale protests and even Diana's sister, Jessica Mitford, described the decision as "a slap in the face of anti-fascists in every country and a direct betrayal of those who have died for the cause of anti-fascism."
After the war Diana and Oswald Mosley established Euphorion Books in an attempt to publish the work of right-wing authors. Diana also edited the far-right magazine, The European. The couple left England in 1949 and after a period in Ireland settled in France where they lived close to their friends, the Duke of Windsor and Wallis Simpson.
The couple returned to England on a regular basis to campaign for the reorganized British Union of Fascists, the Union Movement. They were both strong opponents of non-white immigration. According to Diana: "Immigration has been a tragedy, any number should be allowed in to go to universities and learn to be doctors and one thing and another - but not to settle".
In 1977 Diana published her memoirs, A Life of Contrasts. In the book she attempted to justify her racist beliefs and the support she had given Adolf Hitler in the 1930s.
Diana Mosley died in Paris on 11th August, 2003.