The BBC, which is to air some of the tapes next month, says there were ‘a large number’ of vintage recordings unearthed at his former home in Wavering Down House in Cross, Somerset.
Dennis Heymer, who was Howerd's partner and manager, and Chris Byrne, Heymer's adopted son and carer, still live in the house, which they occasionally open for charity.
Byrne will present the Radio 4 show Frankie’s House, which includes the lost recordings, at 11.30am on Tuesday October 16.
The tapes will be interspersed with the tale of the restoration of the house as it is turned into a museum dedicated to Howerd's memory. June Whitfield will also narrate some of the story.
A BBC spokesman said: ‘Byrne, with his mischievous Irish accent, is the show's principal guide. He tells the stories behind objects in the collection and the incidents, habits and comments from Frankie which they evoke. The show explores the house and grounds and gauges visitors' reactions to some of the extraordinary things on display.’
Among the more unusual items at the house is Howerd’s infamous toupee.
