A Berkshire man aged in his 80s is being interviewed by detectives who are part of the Operation Yew Tree investigation, Scotland Yard has said.
The suspect is being questioned after attending a south London police station by appointment on Thursday.
He is being treated as part of the investigation that does not directly relate to the Jimmy Savile investigation, the Metropolitan Police said.
Before Thursday, four arrests had been made as part of the national investigation into alleged sexual offences by Savile and others.
Gary Glitter, comedian Freddie Starr, DJ Dave Lee Travis and a man in his 70s, reported to be former television producer Wilfred De'Ath, have been arrested and bailed as part of the probe.
Scotland Yard is leading the inquiry and has said officers are currently dealing with around 450 potential victims, the vast majority of whom claim they fell prey to Savile.
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Wednesday afternoon's weather for the east of the region
Wednesday afternoon's weather for the west of the region