Members of the Royal Family will wear black armbands «as a mark of respect» to those involved in the Air India crash at tomorrow’s Trooping the Colour parade.
There will also be a minute’s silence at the event following Thursday’s crash in the city of Ahmedabad, western India.
Following the crash, which killed at least 241 people, the King asked for some amendments to be made to his traditional birthday parade on Saturday.
A palace spokesperson said Charles wanted the alterations «as a mark of respect for the lives lost, the families in mourning and all the communities affected by this awful tragedy».
The minute’s silence will be held after the King inspects the guard on Horse Guards Parade. It will be signalled in the traditional way by a Last Post and Reveille.
Charles and the senior royals riding in the ceremony will wear black armbands, as will postilions, coachmen and coachwomen from the Royal Mews.
They will not be worn by family members who are wearing civilian clothes.
The King said he and the Queen were «desperately shocked by the terrible events in Ahmedabad» after the crash on Thursday.
Please use Chrome browser for a more accessible video player
On the ground at India plane crash site
A statement from Buckingham Palace continued: «Our special prayers and deepest possible sympathy are with the families and friends of all those affected by this appallingly tragic incident across so many nations, as they await news of their loved ones.
«I would like to pay a particular tribute to the heroic efforts of the emergency services and all those providing help and support at this most heartbreaking and traumatic time.»
Union flags have today been flown at half-mast on all royal residences and government buildings.
Alterations have been made to the Trooping event before.
In 2017, Queen Elizabeth requested a minute’s silence to be held during the parade as a mark of respect to those who died in the Grenfell Tower fire three days earlier.
Please use Chrome browser for a more accessible video player
Indian PM meets lone survivor of crash
Read more:
Who are the Air India crash victims?
King meets D-Day veterans
This year, the Coldstream Guards will Troop their Colour and display their banner flag as they mark their 375th anniversary.
A decade later, in 1660, the regiment marched down from Berwick to help restore the monarchy, dissolve Parliament and bring King Charles II back to the throne.
The royals on the balcony at last year’s Trooping the Colour. Pic: PA
More than 1,000 soldiers and 200 horses from the Household Division will be involved in the spectacular display, with members of the Royal Family also taking part on horseback or travelling along the Mall in carriages.
Last year, the King joined Camilla in a carriage, rather than riding, after being diagnosed with cancer months earlier in February.
It’s been reported he will do the same this year, but this has not been confirmed by the palace.
The event will finish with the traditional balcony moment, as members of the Royal Family gather to watch a flypast of military aircraft, including The Red Arrows.