The Natural History Museum in Basel led a team of researchers that uncovered the mystery identity of the body, which was discovered in 1975 while renovations were being done on Basel's Barfüsser Church.
She was buried in front of the church's altar, which local historians said was only permitted for wealthy Basel family members, but there was no gravestone to indicate her identity.
Thanks to the most up to date methods, scientists were able to extract DNA material from the mummy's big toe.
The results presented on Thursday revealed that the mummy was a member of a well-established Basel family, the Bischoffs.
With a 99.8 per cent probability that the descendants and the mummy were all from the same maternal line, the scientists and historians were confident that the mummy is Anna Catharina Bischoff.
She was born in Basel in 1719 and married a pastor in 1738 before giving birth to seven children - with only two surviving childhood.
Her daughter Anna married a man named Christian Hubert Baron Pfeffel von Kriegelstein whose fifth generation relative Marie Luise von Pfeffel married a Stanley Fred Williams. Their daughter Yvonne married Osman Wilfred Johnson Kemal and their son, Stanley Johnson, went on to have Mr Johnson.
Mr Johnson hasn't commented on the discovery of his long lost relative, but he is aware of the von Kriegelstein connection, having once told the BBC programme 'Who Do You Think You Are?' that they were 'posh toffs'.
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