A BBC children's television presenter has been arrested on suspicion of murder after his fiancee was found dead in the bathroom of their London flat, his lawyer and police said on Friday.

Mark Speight, who hosts the art show "SMart", was held at the scene on Thursday and later bailed to return to a police station in early February.

In a statement, Speight's lawyer said the presenter found the body of Natasha Collins in the bathroom of the flat they shared in St John's Wood and immediately called an ambulance and the police.

"Mark was the only other person present in the flat and has therefore been questioned by police as a matter of course," said lawyer Nabeel Sheikh, of London law firm Sabir Selby.

"He is assisting police with their enquiries and had nothing to do with Natasha's death.

"Mark is absolutely distraught at the loss of Natasha and hopes that everyone will appreciate what a very sad time this is for both Mark and Natasha's family."

The statement added that no one yet knows what happened to Collins, who was an actress, TV presenter and model.

A family statement said: "We are all absolutely distraught over the death of Natasha. She was our loving caring daughter who was always full of life."

A Metropolitan Police spokesman said a post mortem was due to take place to establish how Collins died.

"Officers from Marylebone are investigating," he said. "A man in his 40s was arrested at the scene. He remains in custody at a central London police station."

Collins' casting agency, Essex-based HandE, said she was a "wonderful, confident young lady (whose) beauty was inside and out".

"We are shocked and devastated that Natasha has passed away and we offer our support and condolences to her family and friends," it said in a statement.

Her agent Mark French told Sky News: "They were just a really fun couple who were fantastic together."

Speight has appeared on the BBC's religious show "Heaven and Earth", as well as on ITV's "This Morning".

The couple appeared together in the BBC children's programme "See It Saw It".

A BBC spokesman declined to comment. Speight's representative at the theatrical agent Billy Marsh Associates could not be reached immediately.