One of the most portrayed of all detectives, Sherlock Holmes, is returning to the small screen with some unfamiliar assistants.

Faithful Dr Watson is by his side but the Baker Street sleuth will also have help from a ragtag group of street kids.

They're the Baker Street Irregulars, who first appeared in the Holmes novel, A Study In Scarlet, in 1887. They team up with Holmes to combine their skills against one of his greatest enemies, Irene Adler. As the street kids try to solve the disappearance of two of their own gang, Holmes himself is accused of murder and put under house arrest.

The family drama, Sherlock Holmes And The Baker Street Irregulars, is written for BBC1 and CBBC by Richard Kurti and Bev Doyle, whose credits include Robin Hood and Primeval. Jonathan Pryce stars as Holmes, with Bill Paterson as his doctor friend.

The writers point out that they're not actually retelling a story as this is an original based on Conan Doyle's characters. "Really it was the best of both worlds. We were given fantastic building blocks by a great writer and then allowed to take them for a walk wherever we wanted," they say.

"Although Conan Doyle mentioned the Irregulars, he never characterised them or went into who they were, how they'd become Irregulars, where they lived and so on. We were able to play the mind game of trying to imagine what Conan Doyle would have said about them if asked."

Pryce - recently seen as Governor Weatherby Swan in The Pirates Of The Caribbean movies - has always wanted to play Holmes. "It's a role I've always thought I would like to do ever since seeing Basil Rathbone when I was young," he says.

"My great friend Bill Paterson had often said that we should do it together and, when this script arrived, we jumped at it. It's such an iconic role that I was a little nervous about taking it on, but the script focuses on the Irregulars so much that I felt I could sneak up on it. It's very well written and respects the period but, at the same time, feels like a very contemporary piece."

He resisted a too stereotypical approach to Holmes. The deerstalker makes just one appearance and, because it's for family viewing, smoking is discouraged. "As pipe smoking makes me nauseous, I was very happy not to light up," he says.

Watson doesn't spend a huge amount of time with the kids in the way that Holmes does. "But they were delightful and very fast at picking things up. A lot quicker than the adults, in fact," says Paterson.

"They're a real gang of ruffians that first appear in Holmes's office, much to Watson's agony. It's such a nice idea that Holmes has this Fagin-like gang of kids, all of whom are working on the side of good rather than the side of evil, picking pockets. Our little group are working on the side of goodness and morality. There's potential for more stories there."

They're the latest in a long line of small screen Holmes and Watson. The first time Conan Doyle's detective appeared on the box came in 1937 in The Three Garridebs, a trial telecast broadcast from the stage of New York City's Radio City Music Hall. Louis Hector and William Podmore played the pair.

Since then actors who've stepped into Holmes's shoes in TV series and TV movies include Ronald Howard, Peter Cushing, Douglas Wilmer, Frank Langella, Charlton Heston, Roger Moore and Leonard Nimoy.

Basil Rathbone, the most famous big screen Holmes in a series of black and white movies, played him on TV too.

An early BBC series based on the character featured Alan Wheatley, later to play the Sheriff of Nottingham in TV's old Robin Hood series, as Holmes. His Watson, Raymond Francis, went on to star as TV detective Lockhart in No Hiding Place.

Douglas Wilmer, in the 1965 BBC series, was reckoned to bear an uncanny resemblance to the sleuth in the original illustrations. Peter Cushing, another BBC Holmes, returned to the role in the 1980s for C4's The Masks Of Death with John Mills as Watson.

Cushing's Hammer horror co-star Christopher Lee had The Avengers star Patrick MacNee as Watson to his Holmes in two 1999 TV movies. Australian Richard Roxburgh was the most recent TV incarnation in a BBC film of The Hound Of The Baskervilles.

Perhaps the most famous, and for many the best, TV Holmes was Jeremy Brett, who starred in 41 episodes for ITV between 1984 and 1994. They were filmed on a full-scale outdoor replica of Baker Street built at Granada Studios in Manchester. David Burke was his first Watson, later replaced by Edward Hardwicke.

Both Russia and Czeckoslovakia have produced TV series featuring Holmes. Sherlock Holmes In The 22nd Century was a cartoon series and he underwent a sex change for The Adventures Of Shirley Holmes: Detective, an American children's series from the late 1990s.

And when Holmes isn't around, his creator is. BBC4's recent thriller, Reichenbach Falls, didn't feature the Baker Street detective but did have his creator, Sir Arthur Conan Doyle, as one of the characters.

Sherlock Holmes And The Baker Street Irregulars begins on BBC1 on Sunday, March 25 and concludes on April 1.