Three soldiers collapsed during yesterday’s Order of the Garter Ceremony in Windsor Castle which was attended by King Charles and Queen Camilla. 

One video showed a solider in full dress uniform start to wobble when his comrade reaches over to support him to stop him toppling over. 

The struggling soldier was taken away by two other colleagues for first aid. 

During yesterday’s ancient ceremony, temperatures reached 20C although this is worse for soldiers in full dress uniform on the parade ground. 

An MoD spokesperson told MailOnline: ‘We can confirm that three soldiers who felt faint during  the Garter Service are absolutely fine and back in barracks.’

An insider told MailOnline: ‘Healthy people may faint when standing still for a long time (most common in soldiers, a phenomenon called parade ground syncope), because the leg muscles have to be active to help return blood to the heart.

Three soldiers while standing at Windsor Castle during yesterday’s Order of the Garter ceremony

One soldier started rocking backwards and forwards as the 20C heat yesterday caused him to lose control and was about to fall over 

‘The nature of military duties, physical exercise, exposure to heat, and standing for prolonged periods of time (orthostatic stress) is known to trigger fainting.’

The Army has identified reasons why soldiers faint when practising for events such as the King’s Birthday Parade or yesterday’s Garter Ceremony. 

‘The nature of military duties, specifically; exercise, exposure to heat and standing for prolonged periods of time (orthostatic stress) precipitates fainting. 

‘Ceremonial duties, such as this event, expose our soldiers to these stressors but so do many facets of soldier’s work including on operational deployments. 

‘Commanders at all levels are required to complete mandatory Heat Illness Prevention Awareness Training and soldiers have been given guidance on how to reduce the likelihood of fainting over the years.’

Among the members of the Order taking part in the procession were former prime ministers Sir Tony Blair and Sir John Major, along with Baroness Amos.

The Duke of York, a member of the order, did not join the service.

King Charles and Camilla, pictured, attended yesterday’s ancient ceremony

Thousands of people lined the streets as the parade made its way to Windsor Castle

Soldiers at major events such as Garter Ceremony are at risk of fainting because of the length of time they are expected to stand still

Andrew stepped down from public life after the furore over his friendship with convicted sex offender Jeffrey Epstein and paid millions to settle a civil sexual assault case with Virginia Giuffre, a woman he claimed never to have met.

The ceremony heralds a busy period for the royals, with the King and Queen expected at Royal Ascot in the coming days, and the following week they will host a state visit by Japan’s Emperor.

Hundreds of spectators lined the procession route with many taking hampers and camping chairs to add a summer picnic feel to the occasion.

At one point between the procession, William looked over to where the Duchess of Edinburgh and Vice Admiral Sir Tim Laurence were watching the spectacle and grinned.

The installation of new Companions of the Order – including composer Andrew Lloyd-Webber, who has been made a Knight Companion – took place during the service.

Theatre impresario Lord Lloyd Webber, whose hit musicals include The Phantom Of The Opera, Cats, Jesus Christ Superstar and Joseph And The Amazing Technicolor Dreamcoat, attended a private investiture in the castle’s Garter Throne Room earlier in the day.

Also invested were the Duchess of Gloucester as a Royal Lady of the Garter, as well as Lord Kakkar, emeritus professor of surgery at University College London, and Air Chief Marshal the Lord Peach, who have both been made Knight Companions.

The Garter, founded in 1348 by Edward III, is awarded by the sovereign for outstanding public service and achievements.

After the service, the royals took part in a traditional carriage procession back up the hill to the castle.

The carriages travelled quickly and first Charles and Camilla left by coach followed by Edward, Sophie and William together, and then Anne and her husband Sir Tim.