Crowds gathered outside Buckingham Palace on Sunday morning to watch Royal Navy sailors perform the Changing of the Guard ceremony for the first time in its 357-year history.
Eighty-six sailors from 45 Royal Navy ships and establishments spent a month learning the intricate routines before being deemed ready to carry out the event for real.
The ceremony, which has been taking place since the restoration of King Charles II in 1660, is traditionally performed by one of the five Foot Guards Regiments from the Army's Household Division.
The sailors trained at the Royal Navy's headquarters in Portsmouth, with their new skills being polished by drill instructors from the 1st Battalion Coldstream Guards.
They marched through the famous gates to the theme tune of Game Of Thrones watched by thousands of tourists.
Warrant Officer 1st Class Eddie Wearing, the Royal Navy's state ceremonial training officer, said before the ceremony: "It's daunting, but I'm very excited.
"To be the conducting warrant officer for the first mount ever in the Royal Navy is a massive privilege and an honour to do. I'm really looking forward to it."
The roots of the Changing of the Guard ceremony can be traced all the way back to the reign of Henry VII when the first royal bodyguard was created.
Lieutenant Commander Steve Elliott will be Captain of the Queen's Guard.
"As we march out of the Wellington Barracks for the first time I'm fairly sure everyone will feel an enormous sense of pride," he said.
"It's great to do this ceremonial piece and have the Royal Navy in the public eye in this way."
But a group of soldiers from the Grenadier Guards, one of the five Foot Guards Regiments, were not worried they would be upstaged.
One said: "They could be better. They won't ever be able to do it like the Grenadiers can."
He added: "We popped in to the Wellington Barracks last night and they were dead nervous. They've only had a month to train."
Another joked: "We've been doing it for 300 years. It's about time we let [the Navy] have a turn.
"Don't let them say we never do anything for them."
The Royal Navy's turn in the Changing of the Guard ceremony is one of many events staged to celebrate 2017 as "The Year of the Navy".
It marks the arrival of several new ships to the fleet, including the aircraft carrier HMS Queen Elizabeth.