Steve Scully, 70, said he saw the Duke of York fooling around by the pool for several minutes with a bikini-clad blonde which he insists was sex slave Ms Roberts.
Mr Scully, who maintained the internet and phone signal on Little St James for the billionaire paedophile, made the bombshell accusations in an interview with the Sun on Sunday.
Andrew has strenuously denied Ms Roberts allegations that she was forced to have sex with him three times in 2001.
Ms Roberts - now known as Ms Giuffre - also claims she was coerced into having an orgy with Andrew on Epstein's luxury hideaway.'
Read more: 'I saw Prince Andrew groping Virginia Roberts': Witness claims he saw the Duke kissing and holding hands with Epstein sex slave on the disgraced tycoon's infamous 'paedo island'
Former royal protection officer says 'rude' Prince may have stayed at Buckingham Palace and NOT his Sunninghill home as he claimed on night he is accused of sex with Epstein victim Virginia Roberts
'A highly respected former Royal protection officer has raised questions about Prince Andrew's 'alibi' for the night he allegedly had sex with teenage trafficking victim Virginia Roberts.
In an interview with The Mail on Sunday, the officer says he believes the Prince may have returned to Buckingham Palace in the early hours of March 11, 2001 – contradicting his account of being 'at home' all evening after taking his daughter Beatrice to Pizza Express in Woking.
Ms Roberts, then 17, claims that earlier that night she was coerced into having sex with the Duke after being flown to London by serial paedophile Jeffrey Epstein.
Speaking for the first time, the officer – who had an 'exemplary' 23-year career in the Metropolitan Police – recalls how the Duke of York arrived by car at the front of the Palace in the middle of the night and hurled abuse at guards when they did not open the gates quickly enough.'
Read more: Former royal protection officer says 'rude' Prince may have stayed at Buckingham Palace and NOT his Sunninghill home as he claimed on night he is accused of sex with Epstein victim Virginia Roberts