Ms Kingston, who starred in the long running US hospital drama ER and who has also appeared in Dr Who, recently took part in the BBC's 'Who Do You Think You Are' series and made some surprise discoveries - including the fact that one of her female ancestors had once run a brothel.

Her research into her family tree took her to Battersea Library which houses the Wandsworth Heritage Service, because her great grandfather, who was killed in the First World War, once lived in the borough.

By checking the historical documents held by the service she was able to start tracing her family back hundreds of years - and in the process unearthed not only her Jewish roots but also that her great, great, great, great grandmother had once run "a house of ill-repute" in Westminster.

Heritage officer Ruth Macleod, who appeared in the programme helping the actress in her search, said: "We were able to locate her great grandfather and other members of her family from census records, and armed with those details she was able to start her journey back through history.

"This is something we do on a fairly regular basis for people who want to find out more about their backgrounds and the lives of their ancestors. The historical documents we hold are often the key to unlocking some amazing family secrets."

Staff at the heritage service can give people lots of advice on how to start their research and where to look for information, as well as being able to suggest other historical sources that could cast more light on the lives of their relatives. These include:

• Census records from 1841 to 1901
• Electoral registers for Battersea from 1885 and Wandsworth from 1892
• Local newspapers including the Wandsworth Borough News from 1885 to 2006, The South London Press from 1865 to 2006, and The South Western Star between 1889 and 1988.
• Free access to Ancestrylibrary.com in the search room

The service also holds various historical documents that can be used for a wide range of research topics including family history, house history, school projects, local history research and art or drama projects. These include:

• Ordnance Survey maps
• Photographs.
• Town plans
• Records of current and previous governing bodies including the civil parishes, Metropolitan Borough of Battersea, Metropolitan Borough of Wandsworth and the current borough council.
• Diaries and letters of local residents including the poet Edward Thomas
• Records relating to the Second World War
• Records of local organizations including businesses and political parties
• Local history books.