In the end the reaction was fitting: last night's unveiling of David Tennant's replacement in the Tardis was met with a near universal "who?".

The BBC revealed Matt Smith, 26, as the eleventh Doctor, the youngest ever actor to take on the role, upsetting the odds, if not the space-time continuum.

Earlier in the day Paterson Joseph, 44, was odds-on to be the new face of the Time Lord. Other names in the frame had included David Morrissey, Sean Pertwee, and even Catherine Zeta Jones. However, the show's producers said that as soon as they had seen Smith's audition they "knew he was the one".

Smith said last night he is still in a state of shock since discovering he had won the role over the Christmas period: "I'm flabbergasted, I haven't slept really to be honest.

"Doctor Who is an iconic part of our culture; my grandad knows about it, my dad knows about it, it's been going since 1963 and it has the iconic status of Robin Hood or Sherlock Holmes."

Filming begins in the summer for the next full series, which arrives on our TV screens in 2010. Before then David Tennant will appear in four special episodes this year before bowing out of a role he took on in 2005.

"I've got this wonderful journey in front of me," said Smith. "I've got six months to build this Time Lord and that's such an exciting prospect."

Smith grew up in Northampton, where he excelled in both performance and sport. He played for Leicester City Under 15s and 16s, until his dreams of becoming a professional footballer were dashed by a back injury.

He admits he "sort of fell into acting really". His break came while studying at the University of East Anglia, when he was cast in the play Fresh Kills at the Royal Court Theatre.

He went on to join the cast of Alan Bennett's play The History Boys at the National Theatre in London before making his TV debut in the BBC adaptations of Philip Pullman's The Ruby In The Smoke and The Shadow In The North, alongside Doctor Who actress Billie Piper. He also landed the role of Danny, one of the central characters in the BBC Two series Party Animals.

Despite his relatively short acting CV, Smith was the instant choice, according to Steven Moffat, who is taking over from Russell T Davies as the lead writer and executive producer of the show.

"The Doctor is a very special part You need to be old and young at the same time, a boffin and an action hero, a cheeky schoolboy and the wise old man of the universe. As soon as Matt walked through the door, and blew us away with a bold and brand new take on the Time Lord, we knew we had our man."

Anthony Wainer, press and publicity officer for the Doctor Who Appreciation Society, said: "It's a different choice and I'm delighted by it. But I do think it has taken some people by surprise.

"The shadow of David Tennant looms large. He was so great, which makes the job for the next person even harder. But here's someone who is younger, and with that youth comes more enthusiasm. It is the only way you could trump Tennant."

Tom Harris, the Labour MP for Glasgow South and a devout Whovian - the name given to fans of the show - said: "In the Whovian community there's a huge amount of respect for Steven Moffat because he's been the best writer for the past three or four years. So any people with reservations will give Smith the benefit of the doubt because he was Steven's choice."


Goodbye David... When David Tennant replaced Christopher Eccleston in 2005, few predicted the success he would have establishing Doctor Who's long-term popularity among a new generation of fans - or effect it would had on the actor's own career.

With the show's reputation and ratings restored under Eccleston, Tennant, an established TV actor fresh from the lead in BBC drama Casanova, who had also played in Harry Potter And The Goblet Of Fire, was taking a risk.

Had the relaunched show failed to sustain its popularity, the career of the 37-year-old son of a Church of Scotland minister's could have been severely damaged. As with his successor Matt Smith, fans were divided about how good Tennant would be.

As he approaches the end of his four-year stint as the 10th incarnation, Tennant can reflect on a gamble that paid off. His manic, eye-popping portrayal has turned him into one of the most coveted actors in the UK.

Tennant's energetic incarnation connected with fans in a way that some predecessors had failed. Proof came when Doctor Who Magazine readers voted him better than Tom Baker, previously regarded as the finest doctor.

He also struck up rapports with his companions Rose, Martha and Donna, played by Billie Piper, Freema Agyeman and Catherine Tate.

Unlike Eccleston, Tennant had the time to establish his version of the character, but is less forthcoming about his private life and rarely gives interviews.

He announced that he would quit the show after winning the best drama performance award at the National Television Awards in October.

Many expect the actor, who won impressive reviews for his performances in the Royal Shakespeare Company's production of Hamlet, to head for Hollywood after filming his last appearance as the doctor in the 2009 Christmas special.

The Stage has named him as only the fifth actor ever to enter its top 20 power list of the most influential people in showbiz.

... And Russell IT must have been a lucky omen for Doctor Who's spectacular revival that its executive producer Russell T Davies was born in 1963, the year the show originally materialised on BBC television, sending a generation of children scurrying behind their parents' sofas.

Davies, best known for his ground-breaking portrayal of gay men in the 1999 Channel 4 drama Queer As Folk, had been a fan of the sci-fi series since he was a child, despite admitting that poor special effects and dodgy sets had made it a "joke" by the time it was axed in 1989.

When BBC One controller Lorraine Heggessey offered him the job of bringing back the series, Davies had the kind of budget his predecessors could only have dreamed about. He was charged with writing many of the episodes, but the key to the revival's success was the appointment of Christopher Ecceleston as the ninth doctor.

There were initial concerns about the suitability of his new companion, former pop star Billie Piper, who played Rose. However, fears were allayed when she turned in a series of strong performances.

Backed up by superb writing and some colourful monsters that were a world away from the rubber creations the old show's props department came up with, the first episode on March 26, 2005 was an instant ratings success. The BBC swiftly approved a second and third series.

Davies broke new ground by introducing a bisexual character, Captain Jack, played by John Barrowman, and a romantic edge between the doctor and Rose that would have had the 1960s original incarnation - played by William Hartnell - turning in his regenerative grave. The show ably survived Eccleston's surprise decision to quit after one series, and has gone on to attract a number of celebrities, including Kylie Minogue.

It also brought fresh credibility for BBC Wales, with the revived show being shot mainly in Cardiff.

Davies was rewarded with the Dennis Potter award for outstanding writing for TV at the 2006 Baftas, where the series won best drama. He will be replaced by Steven Moffat in 2010 after completing his three specials starring David Tennant.