Claudia friends and family tell of distress

In an emotional TV documentary for Channel 4 last night, Miss Lawrence's best friends Suzy Cooper and Jen King and father Peter Lawrence talked of their fears at how speculation over her love affairs dented public efforts to find the missing 35-year-old who is feared dead.

They hope the prime-time programme will now spur those with information about her disappearance who may not have gone to the police to come forward.

Officers were last night manning special phone lines in the hope potential witnesses would call.

Miss Lawrence was last seen near her home in Heworth Road, York, on March 18 last year, returning from a shift at the University of York's Goodricke College. She was due to go out with friends that night but did not turn up and has not been heard from since.

A massive police search turned up no trace of her and the operation was upgraded to a murder investigation the following month. Police have turned up few leads, however, and have consistently said they believe the vital clues to her disappearance lie in her "complex" relationships.

But Ms Cooper and Miss King revealed their friend would have been appalled at the attention on her private life, and Mr Lawrence, 64, a solicitor from Slingsby, said he had to believe she was still alive since he thought he "would feel something different inside" if she were not.

Police scaled back the inquiry last month but stress the investigation remains open.

A spokesman for North Yorkshire Police said last night the force had received eight calls from members of the public in the first two hours after the programme was aired, and that the response would continue to be monitored over the weekend.