The Duke of Cambridge spent his Saturday helping the British Army prepare for their Trooping the Colour ceremony next weekend.
The ceremony will play a part in the Platinum Jubilee celebration, as with every jubilee for the past 260 years.
This year, the military is trooping the colour of the Irish Guards.
Prince William is the colonel of the regiment, so he suited up and joined in the 90-minute dress rehearsal today.
The Duke watched on horseback as more than 1,500 soldiers and 350 horses carried out complex battlefield drill manoeuvres.
They included Devon-based trooper Samuel Wallace, 24, who is the first practising Rastafarian in the Household Guards.
The army views him as one of its most impressive junior soldiers and he has been made part of the royal escort team for the ceremony.
More than 7,000 guests gathered to watch the soldiers and military horses carry out their drills.
The music included Slattery’s Mounted Fut, a favourite tune of the late Queen Mother, and Long Live Elizabeth, in tribute to The Queen, an army spokesman said.
In addition to the familiar traditional regimental marches there were Irish folk songs and a new composition just for the event – called Bob’s Own – named in honour of the first Colonel of the Irish Guards, Field Marshal Lord Roberts.
This will be the first full Trooping of the Colour on Horse Guards for three years.
It is unclear whether the Queen, who has struggled with recurring mobility issues, will attend.
Buckingham Palace has indicated her attendance will only be confirmed on the day of any event.
Garrison sergeant major Andrew Stokes, who is charge of planning the parade, said: ‘It is a big day in the calendar. I think there is more pressure because it is the start of such a significant week.
‘We need to set the right tone. We are aiming for excellence and hoping the public will get involved and feel there are moments in (the Jubilee celebrations) for them.’
Lieutenant Charles Bashall 24, who will carry the Colour on parade, said it is ‘an incredible privilege’ to be part of the Jubilee event especially as ‘there may never be one again’.
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