Excitement builds ahead of King's Trooping the Colour parade amid hope Princess Kate will make Buckingham Palace balcony appearance

Excitement is building ahead of tomorrow's Trooping the Colour parade amid hope the Princess of Wales could make a surprise appearance on the Buckingham Palace balcony. 

Dozens of forthcoming royal engagements have had to be cancelled and reviewed as a result of the General Election - but the official celebrations of the sovereign's birthday will go ahead as planned.

Last year, young Prince Louis stole the show as he gave a cheeky salute to the adoring crowds on the balcony. He was also seen throwing his fists in the air and pouting as his mother Kate looked at him with pride and amusement.

This year's Trooping the Colour will be the first major royal event which King Charles is attending since returning to public-facing duties amid his battle with cancer.

Charles, 75, will inspect the soldiers from a carriage rather than on horseback, it is understood.

Prince William will also be joining his father for his first significant event without the Princess of Wales - but there is hope she may join the other members of the Royal Family on the Buckingham Palace balcony.

The tradition, which dates all the way back to the 17th century, boasts 1,400 soldiers, 400 musicians as well as over 200 horses. 

Usually the monarch rides down from Buckingham Palace to Horse Guards Parade via The Mall to inspect the troops. 

He then rides back to the palace for the traditional balcony appearance with the wider Royal Family and flypast by the RAF.

But while Charles is personally keen to ride his horse, Noble, a black mare which was a gift from the Royal Canadian Mounted Police, concerns have been raised about how strenuous this could be as he continues treatment for cancer.

Queen Elizabeth herself attended the event in a carriage after 1987.

Royal fans have told of their excitement ahead of tomorrow's event - and are hoping to see Kate 'if she is up for it'.

One said: 'I would love to see Catherine on the balcony, if she if up for it... Let's all pray for good weather on the day and if our Princess of Wales brings some sunshine to the day, all the better! 

Another wrote: 'I reset my annual watch with Trooping the Colour every year since I was a child. When Les Huguenots strikes up you feel like you've made if through another year. Trooping the Colour is a fine tradition.

A third said: 'I'm hoping to attend Trooping the Colour this Saturday, and if The Princess of Wales makes a balcony appearance, it would truly make my year! 

Another posted: 'It's The Trooping of the Colour' ceremony tomorrow and how I love it. I never miss it. Transmission begins c 10.30 am, with coach leaving Buckingham Palace. 

And a fifth said: 'Trooping the colour is such a British thing that I love truly makes me proud to be British.'

Rebecca English, The Daily Mail's Royal Editor, suggested to this week's Palace Confidential that an appearance from Kate  should not be completely ruled out amid 'persistent rumours' she might appear on the balcony.

'What's very interesting, is that when I've asked both Kensington Palace and Buckingham Palace about it this week, it's been not saying a word,' said the royal expert.

She continued: 'I mean look, if she is there. Fantastic. People will be delighted to see her. If she isn't, don't read anything into it because she never said she would be. I think it will be a bonus.'

King Charles will be joined by Queen Camilla and Prince Edward, Princess Anne and Prince William will be on horseback.

'For me, actually, the big question is whether the Princess of Wales will be there on the balcony afterwards, that is a rumour that just hasn't gone away over the last few weeks, Rebecca continued.

'She's made very clear, 'look when my doctors say I'm ready to dip my toe back in, I will happily do that', but it's certainly been a persistent rumour.

'I spoke to somebody a few weeks ago and said 'what do you think?' And they said, 'I wouldn't count on it'.

'But it hasn't gone away, and what's very interesting, is that when I've asked both Kensington Palace and Buckingham Palace about it this week, it's been not saying a word... I think watch this space.'

MailOnline contacted both Kensington Palace and Buckingham Palace.

The royal editor's comments come after the Daily Mirror reported last month that the Princess is thought to be considering walking onto the famous balcony if she is feeling well enough.

Last Saturday, Kate apologised for missing out on a key rehearsal for Trooping The Colour.

The Princess wrote a letter to the Irish Guards, who are presenting their colours to the King this year, saying: 'I hope I am able to represent you all very soon'.

Kate missed out on what would have been her first Colonel's Review. The event is a dress rehearsal for Trooping The Colour and would have seen her take the salute as the new Colonel-in-Chief of the Irish Guards.

The Colonel's Review comes before the King's official birthday celebrations on Saturday June 15, including their traditional Buckingham Palace ­balcony appearance.

It is identical to The King's Birthday Parade, with the exception that some additional mounted officers ride on the latter.

The Irish Guards have responded to the Princess's letter on Twitter, writing: 'The Irish Guards were deeply touched to receive a letter from our Colonel, Her Royal Highness, The Princess of Wales this morning.

'We continue to wish Her Royal Highness well in her recovery and send her our very best wishes.'

Charles, meanwhile, has now been given permission by his doctors to undertake more forward-facing public duties, although officials have stressed they need to carefully review each potential engagement, with adaptations made where necessary to prioritise his recovery.

Last night, it also emerged that the three military horses that got loose in central London earlier this year have been confirmed as having roles in Trooping the Colour.

Five Household Cavalry Mounted Regiment (HCMR) horses were injured after being spooked by rubble being dropped through a plastic tunnel while on an exercise in Belgravia on April 24.

Horses Tennyson, Trojan and Vanquish will take part in the King's Birthday Parade after making 'swift and successful' recoveries and showing 'such aptitude and eagerness', the Army said on Thursday.

Tennyson will be riding in the prestigious Sovereign's Escort at the rear rank of the second division, and will be ridden by the division's most experienced rider, Corporal of Horse Harvey, to provide 'extra confidence'.

Trojan and Vanquish will join the King's Life Guard at Horse Guards, providing the ceremonial guard for the official entrance to the Royal Palaces, the Army said.

All three horses underwent rehabilitation at Hyde Park Barracks and a period of 'expert respite care' at equine charity The Horse Trust following the incident, before returning to service last month.