He is still in a critical but stable condition at Atkinson Morley's Hospital in Wimbledon, south west London, which specialises in brain injuries.

Although he is still in a coma, his agent said he is showing signs of recovery.

Barry Burnett said: "He has responded to movement and sound. We are very pleased about that."

Mr Nimmo, 68, tripped and fell on the stairs at his home on Kensington last Wednesday after he had been out for a meal with Pat, his wife of 43 years.

He underwent emergency surgery to remove a blood clot from his brain the following day and has been in intensive care ever since.