The Queen is moving out of Buckingham Palace on the royal wedding night so the newlyweds and their friends can party away.
Her Majesty, 85, does not want to get in the way of Prince William, Kate Middleton and their 300 chums.
The exclusive bash is expected to go on into the early hours in the palace's 19 state rooms, where guests will enjoy a three-course meal before the dancing.
Prince Charles, Camilla and Kate’s parents Carole and Michael are going.
But sources said the Queen and the Duke of Edinburgh, 89, are expected to head to Windsor Castle following the afternoon reception for 650 guests
And they apparently have no qualms about leaving their home in the hands of the younger royals.
The source said: "There is no particular reason for the Queen and Philip leaving after the afternoon reception other than the fact the evening party is more of a younger occasion.
"They are very happy to leave the palace and will be staying somewhere else for the night.
Sources also revealed yesterday the Queen trusts her family so much no staff have been tasked with making sure drunken guests do not go roaming round the palace.
A source added: "It's not an issue they're concerned with." When the partying finally dies down, William and Kate will pop down the corridor to the stunning Belgian Suite, one of 52 royal and guest bedrooms in the 775-room palace. They will be the only royals staying at the palace on the night.
The couple have organized their celebrations so the number of eyes on them diminishes as the day goes on.
They will marry in front of 1,900 guests in Westminster Abbey at 11 am, with a further two billion people expected to watch the nuptials on TV worldwide.
They will then mingle with 650 friends, family and official guests at a reception hosted by the Queen.
But the part of the day where they can really let their hair down is Friday night with their closest friends and family.
Three of the state rooms will be converted into a nightclub.
Guests include Holly Branson, Ben Fogle, close friends from St Andrews and William's stag night friends including Tom Van Straubenzee and Guy Pelly. Best Man Prince Harry has organized bacon sarnies for those still standing at 6 a.m.
A Buckingham Palace spokeswoman confirmed on Sunday night: "The Queen and Prince Philip won't be staying at the palace on the night of the wedding."
On Sunday Prince William tucked into Sunday lunch with Kate and her family -- and brought a mystery gift with him.
A casually-dressed aide clutching a box wrapped in brown paper was spotted in a fleet of three royal protection cars which pulled up in the driveway of the Middleton mansion in Bucklebury, Berks.
The gift, which was carried into the house, looked the right size for a box of chocolate Easter eggs.
Kate is understood to have spent Monday with her family.