Key points
- Ceremony taking place to celebrate the King's official birthday
- King receives royal salute
- Kate among royals on Buckingham Palace balcony|Watch: Royals wave ahead of RAF flypast
- Watch:Kate's first public appearance this year
- In pictures: Royal children attend parade|Prince Louis distracted by blind chord
- Three military horses that escaped in London take part in celebrations
- Analysis: All eyes on Kate
- Explained: What is trooping the colour?
- Live reporting by Ollie Cooper
The Wales's share a moment on the balcony
The Prince and Princess of Wales shared a moment on the Buckingham Palace balcony earlier.
William endured lashing rain earlier on as he stood with troops in the open outside the palace, while his wife and children Princes George and Louis and Princess Charlotte, travelled in a covered carriage that shielded them from the wet weather.
Eyewitness: Sun shows up at fitting moment
By Rhiannon Mills, royal correspondent
What a finale!
After the crowds, the media crew and the royals on horseback got soaked in the torrential rain, the sun came out for the flypast.
A happy family moment, a chance for the crowds to wish the King and Kate well and a sign of how the support of family continues to help them both on their cancer journeys.
Royals impress despite illnesses
Let's get the thoughts of Stephen Bates, former royal correspondent for the Guardian.
He was impressed by the King's performance despite his illness, albeit from a carriage rather than on the traditional horseback.
"He's still undergoing treatment for cancer, so I don't think you could expect him to be prancing about on a horse," he said.
Despite that, "he looks, fit and in reasonable health", Mr Bates added.
He praised him for standing to attention for much of the parade.
Mr Bates was equally as impressed with the Princess of Wales.
"Everyone who's had a cancer diagnosis in the family knows that feeling as they go through treatment... [they have] good days, bad days, the need for rest, the need for slow recuperation.
"It's obviously been a very serious and difficult period for Princess Kate and she's come through it looking absolutely radiant."
He said he thought she looked "desperately thin", but nonetheless "absolutely gorgeous".
Watch: Royals gather on balcony
Watch the Royal Family gather on the famous Buckingham Palace balcony to greet crowds and watch the RAF flypast.
The Princess of Wales was among them, alongside her three children and the Prince of Wales.
RAF flypast begins
With the Royal Family in position, three chinook helicopters lead the first of 10 waves of RAF aircraft for the flypast.
The second wave features three Typhoon FGR4's bearing the official D-Day markings of black and white around the fuselages.
The third sees a Phenom T1 and two Texan T1s scream past.
Next is a C-17 Globemaster transport plane, before a fifth wave, made up of a Voyager and an A400M Atlas, fly over the palace.
A Poseidon aircraft accompanied by two Typhoon fighter jets is up next, before another two Typhoons accompany a RC135W Rivet Joint.
The eighth wave is made up of three Hawk T2s.
The penultimate waves sees four F-35Bs, known as Lightning for reasons obvious to those watching, roar overhead.
The most eagerly awaited are the famous Red Arrows - and they don't disappoint.
Nine Hawks belonging toThe Royal Air Force Aerobatics Team flytrailing their trademark red, white and blue colours.
Kate among royals on Buckingham Palace balcony
The Princess of Wales is among the royals to make their way out to the Buckingham Palace balcony to watch the RAF flypast.
It's set to begin any second.
The weather has somewhat improved and there are glimpses of blue skies.
Gun salute for King
A 41-gun salute has just been fired by the King's Troop Royal Horse Artillery in the Green Park.
The last time gun salutes were heard in London was to mark a year since the King's coronation in May.
Why 41?
A basic gun salute is usually 21 rounds, fired at 10-second intervals.
However, in Hyde Park and Green Park, an extra 20 are fired because it is a Royal Park - as was ordered by the Board of Ordnance in 1827.
Royal Family to gather on Buckingham Palace balcony
Shortly, we're expecting the Royal Family to gather on the famous Buckingham Palace balcony.
From there, they'll watch the RAF flypast, should weather permit.
We expect them in around 15 minutes.
The balcony was prepared by household staff earlier.
Royal fans (and a prince) brave abhorrent weather
Royal fans, now truly sodden, seem undeterred by the worsening rain.
Pictures don't really do justice just how heavy the rain has been coming down on those watching from the Mall.
They're still out in force, although we have seen what can only be described as an army of umbrellas unfurl in the past few minutes.
It's not just fans that have to brave it, however.
This image shows the Prince of Wales standing guard as the rain comes down on his headdress.
Royals return to Buckingham Palace
Salutes received and inspections completed, the King and Queen have now arrived back at Buckingham Palace.
As we said in our last post, the weather has really turned - with heavy rain lashing down on those gathered to watch.
The decision was made early this morning to make sure the royals were put in covered carriages to protect them from the rain.
The King and Queen were preceded by the Princess of Wales and her children in their own separate carriage.
