A mummified body found in a Swiss churchyard is an ancestor of Boris Johnson, researchers say.
The mummy was found decades ago at Barfuesser Church in Basel but her identity at that stage was a mystery.
Experts at Naturhistorisches Museums Basel now believe her to be Anna Catharina Bischoff.
Bischoff was born in 1719 into a wealthy Basel family and married a pastor before having seven children, two of whom survived to become adults.
She spent most of her life in Strasbourg but returned to Basel for her final five years.
She had contracted syphilis, probably from treating sufferers of the disease.
At the time, treatment consisted of mercury but this is thought to have been what killed her in 1787.
It may also, however, be responsible for the well-preserved state of her body.
One of her surviving children, Anna Katharina Gernler (1739 – 1776), married German aristocrat Christian Hubert Baron Pfeffel von Kriegelstein.
Five generations later, Marie Luise von Pfeffel married Stanley Fred Williams; and their daughter Yvonne married Osman Wilfred Johnson Kemal.
Their son was Stanley Johnson, Boris Johnson’s father.
Mr Johnson responded to the findings on Twitter, writing: “Very excited to hear about my late great grand ‘mummy’ – a pioneer in sexual health care. Very proud.”
The mummy had been uncovered once before – in 1843, during building work at the church.
After that it was buried and its details were noted.
These notes were discovered in 2016, sparking a search for clues.
A team under expert Albert Zink took DNA from the mummy in the hope that this would help identify her.
But there was one big problem: unlike nuclear DNA, which comes from both parents, mitochondrial DNA comes only from the mother.
This meant tracing descendants through records was more difficult, as women took their husband’s name when they got married and this was the name that was recorded in a marriage register.
Researchers and genealogists of the Basel Civic Research Project joined the hunt, reconstructing two independent branches of the family.
Saliva samples from living descendants were compared with the mitochondrial DNA of the mummy and researchers found a 99.8% match.
The museum has described the mummy as the best preserved and “most enigmatic” in Switzerland.