Adolf Hitler's sister-in-law ran a boarding house in Highgate

In January 1939, just a few months before the outbreak of the World War II, hundreds of local residents appeared at court in Highgate for non-payment of rates, the property tax that funded local councils.

Among them was a well-built woman in her late 40s who ran a boarding house in Priory Gardens, just off Shepherds Hill. She had arrears of a little over £9 (the equivalent of almost £800 today). Her name was Mrs Bridget Hitler.

The 1938 electoral register for Highgate ward shows Bridget Hitler living in 26 Priory Road with her son William (Image: Andrew Whitehead)

Bridget's brother-in-law was the German dictator, Adolf Hitler. He was the man whose warped ideas of racial superiority and national destiny were about to plunge Europe, and much of the rest of the world, into war and who was responsible for the horrors of the Holocaust.

Bridget Dowling - at various times she also went by the names Brigid and Cissie - was born in Dublin and as a teenager came across an Austrian man working as a hotel porter. This was Alois Hitler, seven years older than his notorious step-brother, who had walked out of his home in Vienna aged 14 after a row with his father, and drifted into a life of petty crime.

In 1910, Bridget and Alois eloped to London where they married, and then moved to Liverpool, where their only child, William Patrick Hitler, was born.

A few years later, Alois moved to Germany - alone.  In the 1920s, having faked his own death and then married again, Alois Hitler was prosecuted for bigamy. It is said to have been Bridget's intervention that saved him from a jail sentence. When a young adult, Willy seems to have visited his uncle, though Adolf didn't make much effort to keep up with his family. 

Bridget was left with no financial support from her husband, which is why - when living off Shepherds Hill - she took in lodgers. It seems to have been her main source of income. She appears to have managed to prise some money out of her brother-in-law: according to the historian Hugh Trevor-Roper (the Hitler expert whose reputation was compromised when in 1983 he authenticated the totally concocted 'Hitler Diaries') she got a modest allowance paid through the German embassy and her son was given a fairly menial job with a German firm.

Perhaps that explains why, even when Adolf Hitler's name became reviled, Bridget was still happy to be known as Mrs Hitler. Both Brigid Hitler and William Patrick Hitler are - somewhat incongruously - listed in the 1938 electoral register from 26 Priory Gardens, amid the good burghers of Highgate East.

Mrs Hitler's court appearance predictably prompted a flurry of newspaper interest. She was photographed in her kitchen cheerfully boiling a kettle against a backdrop of drying washing. "Nowadays it's a bit embarrassing being Mrs Hitler", she told the Daily Express. "Mind you, I've nothing to say against the Nazis as I've found them."

Two months after her court appearance, Bridget Hitler sailed to New York where she joined her son in a lecture tour designed to cash in on the family surname - and dismissed by the German authorities as a telling of 'unauthenticated and detrimental tales of the Fuhrer'. From then on, the United States was her home.

During the war, she rallied to the allied cause and was photographed working in New York as a volunteer for the British War Relief Society. When her son enlisted, mother and son posed together, with the new recruit holding a newspaper bearing the banner headline: 'TO HELL WITH HITLER'.

Bridget may have made one more attempt to make money out of her surname. She (perhaps) wrote a book entitled 'My Brother-in-Law Adolf', which recounted how Adolf Hitler, when evading conscription in Austria, spent six months in Liverpool in 1911; how she introduced him to astrology; and how she persuaded him to trim the edges of his moustache and so was responsible for the toothbrush-style of upper lip which is forever associated with the Nazi leader.

Cover of The Memoirs of Bridget Hitler (Image: Andrew Whitehead)

The work was only published a decade after Bridget's death as The Memoirs of Bridget Hitler. Trevor-Roper dismissed it out-of-hand. The story of Adolf Hitler's sojourn in Liverpool was 'unconvincing', he declared, though as this was a missing period in Hitler's life it could not be entirely disproven. And he was fairly certain that the memoirs weren't written by Bridget Hitler at all (though of course his record in identifying Hitler-related fakes is a long way from foolproof).

After the war, Bridget didn't want to be further tarnished by the Hitler name. She and her son took the name Stuart-Houston. She died in 1969 and was buried in Long Island; her son was interred in the same grave.

• Andrew Whitehead is a historian and the author of the Curious series of books about localities in North London.