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Document of the Week: Detention Report for Sir Oswald Mosley

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Authored by Dr Charlie Hall
Published on 23rd June, 2025 2 min read

Document of the Week: Detention Report for Sir Oswald Mosley

A report written in support of the decision taken by the Home Secretary, John Anderson, to detain Sir Oswald Mosley, leader of the British Union of Fascists (BUF), in May 1940, under the terms of Defence Regulation 18B.

Our latest “Document of the Week” was chosen by our Senior Curator, Dr Charlie Hall. It comprises a report written in support of the decision taken by the Home Secretary, John Anderson, to detain Sir Oswald Mosley, leader of the British Union of Fascists (BUF), in May 1940, under the terms of Defence Regulation 18B.

This regulation, part of the 1939 Emergency Powers Order, was highly controversial because it permitted the suspension of habeas corpus and allowed for detention without trial. Nevertheless, those detained under its auspices, including Mosley, were entitled to a hearing and a detailed report on their case was prepared by an Advisory Committee.

As the report shows, the Committee were fully satisfied that the detention of Mosley was a necessary and justifiable measure. They agreed with the Home Secretary’s verdict that Mosley and his fellow BUF leaders “had sympathies with the system of Government of a power with which His Majesty was at war” (namely Nazi Germany) and that they might act to sabotage or impede Britain’s war effort if not preventively interned.

The report also sheds light on Mosley’s character and his goals within the BUF. He was described as having “an inordinate ambition”, and aspiring to “the possession of an undisputed and even autocratic power”. Mosley remained in prison until November 1943 and under house arrest until the end of the war.

Where to find this document

This item comes from our primary source collection, The British Union of Fascists, 1933–1953. Comprising almost 8,000 images drawn from files at The National Archives (UK), this collection encompasses both personal papers of BUF members themselves and documents produced about them by the British government. The attitudes, activities, and brief popularity of the British Union of Fascists serve as an important reminder of the division and discord in British society on the eve of, and during, the Second World War. Visit the collection page to learn more.


Authored by Dr Charlie Hall

Dr Charlie Hall

I am a Senior Curator at BOA and a Senior Lecturer in Modern European History at the University of Kent. My research interests lie in conflict, technology and society in the twentieth century, with a particular emphasis on Britain, Europe and North America.

Read all posts by Dr Charlie Hall.

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