The millionaire, who was perhaps best known for his collection of Marilyn Monroe memorabilia, died on Saturday following a short illness.
He was aged in his 70s.
Last year he made £1.5 million after auctioning costumes, jewellery and personal items belonging to Monroe.
His collection included the unforgettable black beaded and sequined dress worn by the actress in Some Like it Hot, which sold for $375,000; a stage gown the actress wore in There’s No Business Like Show Business and the ‘wiggle dress’ designed for the thriller ‘Niagara’, which sold for more than £60,000.
Mr Gainsborough Roberts, who was aged 73 at the time, said that in total the auction had generated £1.45 million for him, but that he had no particular plans to spend the money, apart from eating out with friends and family and continuing to collect items relating to Jersey’s history.