Hartnell was interviewed on the Home Service radio programme Desert Island Discs by host Roy Plomley. The episode was broadcast on 23rd August 1965, around the time of Hartnell's third series as the Doctor. The recording was believed to be lost forever after being erased by the BBC, it has recently been discovered that a 16 minute section of the programme has been recovered.
The recording was available earlier today for a short period of time, but has been removed until an official announcement is made. The interview will soon be available on BBC iPlayer.
Update!You can now listen to the interview here.