Alleged victim Andy Moorse told the BBC that barrister John Smyth QC convinced Simon Doggart to join in committing the sadomasochistic abuse at Winchester College in Hampshire during the mid-1970s.
He alleged that the boys would "bleed everywhere" from the attacks.
Mr Doggart, who has been the headteacher of Caldicott preparatory school in Buckinghamshire for the last two decades, is said to be critically ill and unable to respond to the allegations, the broadcaster said.
There is no suggestion that any pupil at Caldicott Preparatory has ever suffered harm at the hands of Mr Doggart.
Hampshire Police says it is investigating.
Survivors said abuse undertaken at Christian camps run at Winchester College - the oldest public school in the country - amounted to a cult, with victims being told the violence would purge them of their sins.
Two years after assault allegations first emerged in 1982, John Smyth - a leading barrister - moved to Zimbabwe where he founded several Christian camps at which it is claimed he abused youngsters.
The Bishop of Guildford Rt Rev Andrew Watson came forward in February 2017 to claim he survived one occasion of abuse at the hands of John Smyth.
John Smyth is still living as a free man in South Africa.