Scotland Yard was facing questions on Sunday over claims that police protecting Andrew Mountbatten-Windsor effectively acted as bouncers for a dinner party thrown by Jeffrey Epstein.
Newly released emails suggest taxpayer-funded protection officers were instructed to provide security for a celebrity soiree thrown at the paedophile's New York home in honour of the visiting royal.
The revelation risks dragging one of the King's most senior aides into the scandal as Peter Loughborough was the head of the Met's royal protection squad at the time of the event in 2010, before he became Lord Steward of the Royal Household.
Emails released by the US Department of Justice suggest two royal protection officers from the Metropolitan Police were told by Epstein's staff to guard the door of his East 71st Street townhouse as guests attended the dinner on December 2, 2010.
Andrew has previously claimed that he travelled to New York solely to 'cut ties' with Epstein after his conviction for soliciting child prostitution in Florida in 2008. The pair were famously pictured chatting and walking in Central Park.
But it has since emerged that Epstein threw a lavish dinner party for Andrew, inviting guests including Hollywood director Woody Allen, US news anchors Katie Couric and George Stephanopoulos, comedian Chelsea Handler and Charlie Rose, a talk show host.
Sir Mick Jagger was also invited, but was unable to attend.
In an email entitled 'Security for party', a member of staff wrote to Epstein saying: 'The Duke's 2 protection officers along with state security will all be here for tomorrow's dinner party... Rich has given them instructions on the door. Do you wish Rich to stay for the party or is it ok for him to go home?'
Newly released emails suggest taxpayer-funded protection officers were instructed to provide security for a soiree thrown at Jeffrey Epstein's New York home in honour of Andrew Mountbatten-Windsor (pictured)
Sex offender Epstein (pictured) threw a lavish dinner party for Andrew, inviting guests including Woody Allen, Katie Couric, George Stephanopoulos, Chelsea Handler and Charlie Rose
Former prime minister Gordon Brown (pictured) has demanded a police investigation into whether Andrew used taxpayer-funded jets and RAF bases to meet up with Epstein
The reference to 'state security' indicates that US diplomatic protection officers also attended. 'Rich' is believed to be Richard Barnett, Epstein's chief engineer and security fixer.
On Friday, the Met said it was contacting Andrew's former protection officers to establish whether they witnessed any potential wrongdoing.
In a toughening of previous language, the force said: 'They have been asked to consider carefully whether anything they saw or heard during that period of service may be relevant to our ongoing reviews and to share any information that could assist us.'
The force has not commented on the latest email regarding protection officers at the event.
It comes as former prime minister Gordon Brown demanded a police investigation into whether Andrew used taxpayer-funded jets and RAF bases to meet up with the paedophile.
In letters sent to six police forces, he has called for civil servants to be hauled in for questioning about the former Duke of York's time as a trade envoy between 2001 and 2011, including almost three years when Mr Brown was in No 10.
The former Labour leader has asked police to interview officials at the Ministry of Defence, Department for Transport, Foreign Office and the Treasury over Mr Mountbatten-Windsor's conduct.
On one occasion, a jet carrying Epstein and his madam Ghislaine Maxwell landed at Luton airport before going to RAF Marham with two additional passengers, one of whom was listed as an unnamed 'female', according to flight logs.
