Sherlock actor Benedict Cumberbatch is distantly related to Sir Arthur Conan Doyle who wrote the original books, researchers have claimed.

In a piece of sleuthing Holmes himself might have been proud of, Ancestry.com said it had established that Mr Cumberbatch, 40, and Sir Arthur, who died in 1930, are sixteenth cousins, twice removed.

Their common ancestor was John of Gaunt, duke of Lancaster, fourth son of King Edward III and the father of Henry IV.

John of Gaunt, who died in 1399, was Doyle’s 15th-great-grandfather and Cumberbatch’s 17th-great-grandfather, according to the website.

Sir Arthur was born in Edinburgh in 1859, and made a living as a doctor as well as being a prolific author.

Like old Harrovian Mr Cumberbatch, he attended private boarding schools as a child – paid for by wealthy relatives after his parents fell on hard times.

This isn’t the first time researchers have delved into the history of the Cumberbatch family and discovered a curious coincidence.

The same team of genealogists found the actor was “distantly related” to Bletchley Park codebreaker Alan Turing, who he played in the biopic The Imitation Game.

Sherlock season 4 in pictures Show all 7 1 /7 Sherlock season 4 in pictures Sherlock season 4 in pictures Mark Gatiss and Benedict Cumberbatch in Sherlock Sherlock, Season 4 premieres January 1, 2017 on MASTERPIECE onÂ PBS. Picture shows: Mycroft Holmes (MARK GATISS) and Sherlock Holmes (BENEDICT CUMBERBATCH) Copyright: Hartswood Films 2016. Sherlock season 4 in pictures Una Stubbs as Mrs Hudson in Sherlock Sherlock, Season 4 premieres January 1, 2017 on MASTERPIECE onÂ PBS. Picture shows: Mrs Hudson (UNA STUBBS) Copyright: Hartswood Films 2016 Sherlock season 4 in pictures Mark Gatiss in Sherlock Sherlock, Season 4 premieres January 1, 2017 on MASTERPIECE onÂ PBS. Picture shows: Mycroft Holmes (MARK GATISS) Copyright: Hartswood Films 2016. Sherlock season 4 in pictures Toby Jones in Sherlock Sherlock, Season 4 premieres January 1, 2017 on MASTERPIECE onÂ PBS. Picture shows: Culverton Smith (TOBY JONES) Copyright: Hartswood Films 2016. Sherlock season 4 in pictures Martin Freeman in Sherlock Sherlock, Season 4 premieres January 1, 2017 on MASTERPIECE onÂ PBS. Picture shows: John Watson (MARTIN FREEMAN) Copyright: Hartswood Films 2016. Sherlock season 4 in pictures Martin Freeman, Amanda Abbington, and Benedict Cumberbatch in Sherlock Sherlock, Season 4 premieres January 1, 2017 on MASTERPIECE onÂ PBS. Picture shows: Behind-the-scenes filming 'Sherlock' Season 4. John Watson (MARTIN FREEMAN), Mary Watson (AMANDA ABBINGTON) and Sherlock Holmes (BENEDICT CUMBERBATCH) Copyright: Hartswood Films 2016. Sherlock season 4 in pictures Amanda Abbington, Benedict Cumberbatch, and Martin Freeman in Sherlock Sherlock, Season 4 premieres January 1, 2017 on MASTERPIECE onÂ PBS. Picture shows: Mary Watson (AMANDA ABBINGTON), Sherlock Holmes (BENEDICT CUMBERBATCH) and John Watson (MARTIN FREEMAN) Hartswood Films 2016

The Cumberbatch family tree came under close media scrutiny after the actor worked on the film Twelve Years a Slave when it was revealed another of his ancestors was involved in the slave-trade in Barbados.

Further scrutiny of the Cumberbatch family tree revealed his third cousin twice removed, Noel Carlisle Rees, was responsible for smuggling thousands of Allied soldiers out of Greece during the Second World War while working for British military intelligence.

A new three-part series of the BBC’s enduringly popular Sherlock returns to television screens on Sunday night, with Mr Cumberbatch resuming the role he has played since 2010.

Fans fear this latest series could be the last starring Mr Cumberbatch and co-star Martin Freeman as his sidekick Watson, with both actors enjoying growing profiles in Hollywood after their film work.

When asked about the likelihood of him appearing in another series, Mr Cumberbatch told the Daily Mail: “This new series goes to a place where it will be hard to follow on immediately.