As you'd expect, there are some strict rules that people invited to attend the Coronation must attend.
Alongside some very detailed guidance on outfits, naturally, there are expectations on behaviour during the ceremony as King Charles and Queen Camilla are crowned.
Invited guests include David and Victoria Beckham, Stephen Fry, Prime Minister Rishi Sunak and US First Lady Jill Biden but her husband President Joe Biden will not be attending.
All attending guests have been warned to not use cameras, video, or sound recording equipment.
They must ensure that mobile phones and other electronic devices are switched off and during the music before the service, they're warned to keep conversation to a minimum.
People attending the coronation service began filing into Westminster Abbey at just after 7.30am - with Stephen Fry spotted entering at 7.45am.
Dozens poured into the church wearing suits, fascinators, military uniforms and medals and religious clothing.
Sniffer dogs had been patrolling the area shortly before the guests filed in to the Abbey.
The coronation ceremony will end at 1pm and the newly crowned King and Queen will begin the procession back to Buckingham Palace in the gold state coach.
Some 4,000 sailors, soldiers, aviators and other military personnel from across the UK and the Commonwealth will accompany Charles and Camilla on their return procession. There will be more than 1,000 route liners from the Army, RAF and Royal Navy.
Charles and Camilla are expected to enter Buckingham Palace through the centre arch at 1.33pm.
They will receive a salute from the military in the palace gardens at 1.45pm, and then at about 2.15pm they will be joined by members of the royal family on the palace balcony to watch the flypast.
Last night, the King has hosted heads of state from around the world at a Buckingham Palace reception on the eve of the coronation.
The Prince and Princess of Wales, the Duke and Duchess of Edinburgh, the Princess Royal and Vice Admiral Sir Tim Laurence also greeted their overseas guests at the event.
Completing the royal contingent were the Duke and Duchess of Gloucester and the Duke of Kent.
The event was the last of several engagements by the royals on Friday.
Among the guests were First Lady of the United States, Jill Biden, who was seen speaking animatedly with Kate.
Meanwhile, Charles was photographed sharing warm words with the First Lady of Ukraine Olena Zelenska, and greeting Mary, Crown Princess of Denmark, with a handshake and a kiss on the cheek.
Other dignitaries at the event included King Felipe VI and Queen Letizia of Spain, the President of Israel Isaac Herzog and his wife Michal, and President of the European Commission Ursula von der Leyen.
Earlier, the King was joined by realm prime ministers and governors general for a Buckingham Palace lunch.
There were 42 at the event, including the Prime Minister Rishi Sunak, Australian prime minister Anthony Albanese, and prime minister of New Zealand Chris Hipkins.
