Army colonels have welcomed the news that the King will attend Trooping the Colour, but said it means they will “have to step up our game even more”.

Charles, who has recently returned to public-facing duties while receiving treatment for an undisclosed form of cancer, will take part in the ceremony on June 15, but will inspect the soldiers from a carriage rather than on horseback as he has done previously.

Meanwhile, the Princess of Wales, who is undergoing chemotherapy, will not inspect the troops at the rehearsal known as The Colonel’s Review on June 8 and it remains unclear whether she will attend Trooping the Colour a week later.

Speaking to the PA news agency at the parade dress rehearsal, Brigade Major Lieutenant Colonel James Shaw said confirmation of King’s presence was “wonderful” but means the army “have to step up our game even more”.

Lt Col Shaw, who will lead the royal procession down the Royal Mall on the day, said: “Firstly, that’s fantastic news but secondly that means we have to step our game up even more.

“It’s just wonderful. I think the King’s service at the moment is an inspiration to us all, he’s our Colonel in Chief so the birthday parade needs to be even better than normal.”

Field Officer in Brigade Waiting, Lieutenant Colonel James Coleby, agreed that the King’s presence added to the “splendour” of the parade.

He said: “For us, it adds to the splendour of the day. Of course, it’s His Majesty’s birthday and we all wanted him to be there and are very pleased he is too and for the journey he’s been on.

“We wish him all the very best, I’m sure there’s more to come in his recovery.

“For him to be on the parade itself – he’s our Colonel in Chief, why wouldn’t we want him to be on the parade with us?

“And of course, when we march off the parade he sits at the head of us all so it’s him leading his own troops off parade which is a lovely thing to do.”

Lt Col Coleby will shout commands on horseback for the foot guards on the day, and has been practising for months, which involves strengthening his vocal cords.

He said: “It has taken weeks of practice and strengthening the throat, and learning how to breathe a little bit better.

“It’s the same as practising drill, you have to practise giving the words of command and it just gets better with practice.”

Lt Col Coleby said the army has rehearsed every day since April, but that “mentally I’m going through it five or six times a day”.

He added: “We have been on and off pretty much since April, rehearsing this parade. So probably once a day we go through this parade, but of course, mentally I’m going through it five or six times a day.

He said that he needed “a loud voice, a well-practised voice and hopefully no hay fever”.

Brig Maj Lt Col Shaw, leading the march down the mall, said that the noise and the atmosphere of the day itself were unparalleled to any practise run of the event.

He said: “You just see the mall stretched out in front of you, the crowds cheering and clapping and that’s what you don’t get today – it’s the noise and atmosphere.

“And then seeing the King and the members of the Royal Family and just that wonderful sea of colour with red tunics – it’s very special.”

Lt Col Coleby, on the other hand, said that shouting commands to his troops was a “lonely” experience. This year will be his sixth Trooping the Colour.

“This is the epitome of how to feel lonely because nobody will do anything unless you tell them to do it with a word of command,” he said.

“You’re on the horse in the middle and then you have to go up to the front, so you’d be surprised how much of the parade I don’t get to see because everything is behind me so I have to have faith.”

Lt Col Coleby also said that despite the military precision, no parade was ever the same: “I don’t think two parades have ever really been exactly the same because the time and weather and circumstances just change.”

He added: “We’ve rehearsed this so many times we know what to do when something does go wrong, where we can tweak and adjust accordingly.”