The 68-year-old was transferred to Chelsea and Westminster Hospital, London, before Christmas from the Atkinson Morley Hospital, Wimbledon, where he had undergone brain surgery following the accident.

A hospital spokesman said the actor remained in intensive care, but that his condition was "stable".

Mr Nimmo was badly injured when he fell down the stairs at his home in Kensington, west London, on 2 December. He had returned from a meal with Pat, his wife of 43 years.

He underwent emergency surgery to remove a blood clot from his brain the following day.

A week after the accident, his agent Barry Burnett said he had started to respond to movement and sound.

Now working as a theatre impresario, Nimmo overcame a stutter to launch a comic acting career in the 1960s.