Filming is currently underway in Tenby for the award-winning hit BBC One drama Sherlock, starring A list celebrity Benedict Cumberbatch.

Crowds have been gathering on the town’s South Beach this afternoon in the hope of catching a glimpse of the star, who takes the title role of the nation’s favourite detective in the acclaimed production which has become a global phenomenen.

Amid high security, scenes for the fourth series are being shot on and around the historic St Catherine’s Island and fort today (Monday) and tomorrow (Tuesday).

Hopes are high that 39-year-old Cumberbatch will soon make an appearance, along with The Office actor Martin Freeman, who plays Sherlock Holmes’ side-kick, Dr John Watson.

The three-part series is expected to air at the end of the year.

St Catherine’s Island is leased by Pete Prosser of the Tenby Island Project which has re-opened the island and its 19th century fort to the public.

“This is a fantastic promotion opportunity for us, but particularly for Tenby and Pembrokeshire,” he said.

“Because of the global viewing figures for the series, this will showcase Tenby to the entire world.”

The massive world-wide acclaim of Sherlock is reflected in its following of nearly 5.5 million for the series’ official Facebook page.

The drama - set in 21st Century Britain - is being produced by Hartswood Films and the fourth series features three new episodes which the BBC says will promise “laughter, tears, shocks, surprises and extraordinary cases” in a reimagining of the Arthur Conan Doyle classic tales.

Sherlock: The Abonimable Bride, which aired on New Year’s Day this year, was the most watched programme over the festive season, and was released in thousands of cinemas around the world to complement the TV broadcast.

It was a particular hit in China, topping box office figures in the first week of its release.

A number of film-related vehicles are currently occupying the lower Salterns car park in Tenby, which the production company has secured on a two-day licence from its owners, Pembrokeshire County Council.

Councillor Rob Lewis, cabinet member for transportation and major events, said: “Sherlock is one of the BBC’s biggest shows and we’re delighted to welcome the cast and crew to Pembrokeshire.

“Our county always looks good on film and I’ve no doubt the exposure it will receive will boost visitor numbers in the future.

I’m not sure when it will be shown on tv but I’ll definitely be tuning in to watch. I’m a big fan of the show and it will be interesting to see how St Catherine’s Island will feature in the story.”

This will be the second time that Benedict Cumberbatch has filmed in Pembrokeshire. In 2010, he took the lead role in the film Third Star, which was shot on and around Barafundle Beach. The film was written and produced by Vaughan Sivell, who grew up in Penally, and tells the story of a young man dying of cancer who decides to make a final camping trip with his best friends to Barafundle.

Have you caught Sherlock or Dr Watson on camera at Tenby? Send your pics to wtnews@westerntelegraph.co.uk