The Hampstead actor Benedict Cumberbatch has taken London’s most famous detective into the 21st century with the BBC series Sherlock. He tells Marianne Gray of his love for Arthur Conan Doyle’s character and the pressure of bringing him back to the small screen.

I DOUBT whether Arthur Conan Doyle is turning in his grave over the BBC's modern look at London's favourite fictional detective, Sherlock Holmes, in their trio of Sunday night films called Sherlock.

Starring Benedict Cumberbatch as Sherlock Holmes and Martin Freeman as Dr Watson, this is Sherlock Holmes for a new generation and, as Cumberbatch comments, Conan Doyle's books have provided a hugely broad church and given people great scope for freedom and interpretation, which these three films have grabbed with both hands.

"The original novels were so gripping and well thought-out with beautifully drawn characters they gave a fantastic insight into very extraordinary people," says Cumberbatch. "We pay homage to these original stories which were written more than a 120 years ago, but have updated them to now.

"We see Holmes using his skills in a different era. He uses contemporary technology and forensic science but there still is a huge amount of human instinct needed. He is fallible but he completely fits in with the modern mode of policing.

"I don't see why Sherlock Holmes purists would be upset by our version.The updating work surprisingly well. It's not naff, like doing Julius Caesar with laptops."

His Holmes is a cold, almost alien-like man, fast and lean with a good line in humour, and Freeman's Watson is the person who humanises him. They meet in a similar way as they do in the original story, through a mutual friend from St Barts Hospital, and agree to share a flat at 221B Baker Street where the landlady is Mrs Hudson, played by Una Stubbs.

Sherlock here is a 21st-century detective rather than a 19th-century sleuth. There's not a deerstalker hat or pipe in sight, he is called a "consulting detective" and makes his deductions more on his mobile phone in the back of a black taxi than on his watch in the back of a horse-drawn cab. He plays the violin and has his very own website, The Science of Deduction.

Freeman's Dr Watson is, like Conan Doyle's original, an ex-soldier returning wounded from the war in Afghanistan. This version, co-created by Dr Who writers Steven Moffat and Mark Gatiss (The League of Gentleman) and directed by Paul McGuigan (Lucky Number Slevin) and Euros Lyn (Dr Who), comes when Sherlockmania seems to have reached its height with last year's Guy Ritchie/Robert Downey Jr film, the current play starring Peter Egan called The Secrets of Sherlock Holmes on in the West End and the new Nintendo DS game Sherlock Holmes and the Mystery of Osborne House high in the charts.

"I'd read the books when I was young and watched Basil Rathbone in black and white and Jeremy Brett in colour as Holmes on screen and realised I had huge shoes to fill," says Cumberbatch.

"In so many ways it has been done superlatively well but the principles remain the same even when put in a contemporary setting and London, of course, remains at the heart of the drama. These stories are pieces of exciting adventure which lend themselves incredibly well to a modern setting.

"We went back to the original novels as our source and tell the story from the very beginning, from its inception. The first episode, A Study In Pink, is partly an homage to Conan Doyle's first story to feature Holmes, A Study In Scarlet, written in 1887."

Cumberbatch, 34, with his blue eyes, interesting face and velvety voice, laughs now when recalling the shoot, largely in Cardiff and Newport early last year during the coldest winter in Britain for 30 years. It was freezing and he developed pneumonia with a temperature of 39.4 degrees. Co-star Freeman, best-known for his role as Tim Canterbury in the comedy series The Office, slipped on some steps and ended up with a broken wrist in plaster.

The pair were also snowed in inside a morgue in Merthyr Tydfil - tractors had to be brought in to drag trucks out of the mud and frequently Cumberbatch had to clutch a hot water bottle to his cheeks in order to articulate Holmes's quick-fire deductions.

Currently on stage at the National Theatre in the Terence Rattigan play After The Dance as David Scott-Fowler, Cumberbatch is perhaps best-known for his portrayal of Stephen Hawking in the BBC drama Hawking. More recently we have seen him in Atonement, Small Island and as Vincent Van Gogh in the drama-documentary Van Gogh : Painted with Words. London-born and the son of two TV actors, Timothy Carlton (who changed his name from Cumberbatch) and Wanda Ventham, he was educated at Harrow, where he played Helena in A Midsummer Night's Dream aged 14. He went on to study drama at the University of Manchester and for a while toyed with the idea of becoming a barrister but didn't.

He tells a touching story about how, when he was 19, he acted in Glengarry Glen Ross and afterwards his father said to him that he felt his son was a better actor than he was or ever would be and urged him to make a living out of acting.

For a year he took a drama course at the London Academy of Music and Dramatic Art, and has worked ever since, serving his time doing Shakespeare at the Open Air Theatre in Regent's Park, at the Almeida Theatre from 2004 to 2006 and then at the Royal Court.

His domestic life is shared with girlfriend, actress, writer and comedian Olivia Poulet. They met at Manchester 12 years ago and live near Hampstead Heath and he likes to swim in the ponds.Cumberbatch knows that after

Sherlock his face will become recognised in households across Britain.

He has two films due to be released and is taking riding lessons to play Major Stewart in Steven Spielberg's film of the National Theatre's play War Horse. But first there's Sherlock Holmes.

"I'd be thrilled if part of the effect these three BBC films have is that

viewers wanted to go out and read the original books," he says in that

wonderful voice of his.

"That would be fantastic.