A little-noticed detail in the royal couple’s wedding plans will come as a surprise to the royal family and their many friends and allies, according to a group of senior British royals and the head of Buckingham Palace.

On Wednesday, British Prime Minister David Cameron will announce the royal party will be invited to the annual Christmas party of the Queen’s Family at Buckingham Palace for a celebratory reception, where they will be joined by friends and family, but there will be no royal wedding.

The Buckingham Palace ceremony is expected to be one of the largest in the history of the British monarchy, but this year’s festivities will be far smaller, with fewer guests than in recent years.

The first royal party to be hosted at the palace in more than 100 years, this year is the Queen and Prince Philip’s annual Christmas Party, which will be attended by more than 400 guests.

The invitation, issued by the Queen on Wednesday, does not mention the party or the Queen herself.

However, it is understood the royal household has been invited to attend.

A Buckingham Palace source told the AP that the invitation was sent to guests in advance of the party’s official unveiling.

A spokeswoman for Buckingham Palace declined to comment on the invite.

The party, which is scheduled for Dec. 24, is not the first time the Queen has been asked to attend the ceremony.

Her father, the Prince of Wales, once hosted the event in 1952.

The Queen’s family has been staying at the Kensington Palace hotel since December to be with her husband and the Prince, a former Royal Marine who served in Afghanistan, before heading to the White House in Washington for his first official meeting with President Barack Obama.

The ceremony will be hosted by the British ambassador to Washington, Matthew Rycroft, the AP has learned.

Rycroft’s official title is a spokesman for the British government’s official foreign policy.