Wartime diary unmasks double agent after 80 years: Identity of British spy 'Agent Mullet' who double-crossed the Nazi's has finally been revealed after discovery of journal left in family home

An unearthed diary has finally led to the identification of WW2 Agent MulletThe diary was written by Belgian-born Irene Thornton on a dairy farm near BristolResearchers now believe Mrs Thornton's nephew Ronald was the double agentRonald Thornton fled Nazis in Belgium and lived in London until his death in 1969

A Second World War diary has helped researchers finally piece together the identity of the British secret serviceman known only as Agent Mullet.

The diary, written by a Belgian woman named Irene Thornton on a dairy farm near Bristol, records the movements of her husband’s nephew Ronald Thornton, who researchers now believe was the British double agent.

Agent Mullet famously passed on disinformation about British invasion plans to the Nazi regime, thwarting German intelligence and buying the Allies more time to prepare.

Historian Andrew Drake believes Thornton and Mullet are one and the same based on details from the diary, which matches MI-5 information about Mullet’s background.

Mr Drake also tracked down Thornton’s grandson Alan Thornton, living in London, who heard stories about his grandfather’s heroics as a child.

Alan said: ‘[My grandfather] told my dad about some of his wartime capers, but that was all just word of mouth.

‘I’ve scanned over some of the extensive files related to Mullet and many details tie in exactly with what my dad told me, as well as my dad’s accounts of escaping Belgium and a journey to Lisbon, so we’re 100 per cent sure.

‘It was nice to finally pin down Ronald’s code name and to learn that all the second hand information turned out to be backed up by the files.’

Ronald Thornton, now identified as the true Agent Mullet (pictured right), with his children in England after fleeing the Nazi regime

Debra Britton, 65, with the historic diary at her home in Backwell, Bristol

The diary, written in a mixture of English and French, was penned by Belgian-born Irene Thornton, whose husband Michael was Ronald Thornton’s uncle

Irene and Michael Thornton, pictured outside their home in Coombe Dingle near Bristol in the 1940s

The diary, written in both English and French, was written by Belgian-born Irene Thornton, who lived in Coombe Dingle near Bristol.

Mrs Thornton moved to Britain with her English husband Michael in the 1930s to escape the Nazis.

Stunned Debra Britton, 65, inherited the diary from her grandmother Florence Gearing, who was the Thorntons’ housekeeper and was entrusted with the diary after the war.

The diary records details of Irene’s life in the countryside.

Mullet assisted fellow agents Puppet and Hamlet to pass disinformation about British invasion plans back to the Nazis.

They were all ‘double cross’ agents – the Nazis believed that they were loyal to them but actually they were working for the British.

The MI-5 files are heavily redacted – meaning finding the real people behind the code names has always been a challenge.

But experts say the diary has helped them find Ronald’s surviving family – who were able to provide details of his movements during the war.

Researchers say the new information confirms he was Mullet.

Care advisor Mrs Britton said: ‘I remember my dad showing the diary to me when he was reminiscing about the war.

‘He told me to look after it as it was local and family history.

‘It has always been in this house – just placed on his bookshelf with hundreds of others and it remained in the family home until my parents passed away.’

Mr Britton described the diary as ‘a day-by-day account of the 1941 Bristol blitz air raid’, which depicts a ‘very different war to what most were living’.

On January 2, 1940, Irene wrote: ‘It snowed. Coombe Dingle is marvellous under its white coat.

‘This morning, 6am – alert followed by all clear. Then 7am, new alert and all clear at 8am*. 6.50pm air raid warning, spent the evening in our shelter.

‘A quantity of Jerrys passing above us and some serious rounds of gunfire.’

Extracts of Irene’s diary were published online as part of the Sea Mills 100 project’s website to mark VE Day.

They caught the interest of independent researcher Andrew Drake.

Andrew had found released MI-5 files at the National Archives in Kew which detailed the activities of Mullet, Puppet and Hamlet.

In them, Mullet is described as ‘a British subject born [redacted] in Belgium, of a [redacted] father and a [redacted] mother.

Experts say the diary has helped them find Ronald’s surviving family – who were able to provide details of his movements during the war

Mrs Britton’s grandparents Florence and Harold Gearing during the war. Florence was the Thorntons’ housekeeper and was entrusted with the diary by a widowed Irene Thorton in 1945 before she moved back to Belgium

Mrs Britton described the diary as ‘a day-by-day account of the 1941 Bristol blitz air raid’, which depicts a ‘very different war to what most were living’

Extracts of Irene’s diary were published online as part of the Sea Mills 100 project’s website to mark VE Day, where it caught the interest of independent researcher Andrew Drake

‘He was educated in Belgium and in Paris, and has been in business (principally [redacted]) in Belgium most of his life.

‘He is in many ways more Belgium than English and his wife, [redacted] is a member of a well-known Belgium family.’

Having read about the diary on the Sea Mills 100 website, Mr Drake looked for family members whose movements matched those of Mullet before settling on Ronald Thornton.

Eric Thornton ran a shipping business in Bristol – E Thornton and Son Ltd.

He died in 1945, and his wife, who was 22 years his junior, entrusted her diary with their housekeeper and moved back to Belgium. She remarried and lived until 1981.

Ronald Thornton, who died in 1969, could not return to Belgium after the war.

Having read about the diary on the Sea Mills 100 website, Mr Drake looked for family members whose movements matched those of Mullet before settling on Ronald Thornton

Researchers say the new information confirms Ronald Thornton was Agent Mullet

Care advisor Mrs Britton said: ‘I remember my dad showing the diary to me when he was reminiscing about the war. He told me to look after it as it was local and family history’

The National Archives and ‘selected Historical Papers relating to MULLET: British’ from 1943 state:

‘MULLET worked pre-war in Brussels.

‘Having escaped to Lisbon via France he was cultivated by HAMLET (see KV/2/327), who purported to represent anti-Hitler Germans who wished to establish contact with the British Authorities.

‘In fact, as is confirmed by ISOS traffic, HAMLET appointed MULLET as his commercial representative in Great Britain, assisted by PUPPET (see KV/2/329).

‘MULLET and PUPPET provided commercial cover for secret writing correspondence between ‘agents’ in Great Britain and HAMLET in Lisbon until 1944 when the Abwehr lost interest in the case. PUPPET’s material included British disinformation concerning, among other things, the invasion plans.’