Sean Coughlan
BBC News, royal correspondent

Image source, PA Media

This is not the first time the ill health of a monarch has meant changes to Jubilee services of thanksgiving.

For Queen Victoria’s Diamond Jubilee in 1897 she wasn’t able to get up the steps of St Paul’s - so the service was held outside instead.

She stayed in her carriage during the ceremony, in what must have been an early version of a drive-in church service, with the clergy, choir and congregation of dignitaries gathered around outside.

It was said that the service of prayers and music only lasted 20 minutes, before she rode in her carriage through the streets of London and back to Buckingham Palace.

Guests and dignitaries are beginning to file into the cathedral. The royals are expected to arrive there at about 11:00am.

As we've reported the Queen won't be going, but which royals will?

• The Prince of Wales and his wife Camilla, Duchess of Cornwall, with Prince Charles officially representing the Queen.
• The Duke and Duchess of Cambridge will attend but it's not known if their children will join them
• Prince Harry and Meghan will be there in their first royal event together since leaving the UK two years ago
• Many other royals are expected to attend but Prince Andrew won't be going after testing positive for Covid

Other guests include lord lieutenants representing every county of the UK, alongside the PM, Cabinet members, first ministers of the devolved governments, opposition leaders and, as we've seen, former PMs.

Representatives from UK overseas territories and governors general are attending, along with high commissioners and ambassadors from across the world.

A large number of representatives of world faiths are also at the cathedral.

The Dean of St Paul's Cathedral says the service has been a year in the making.

The Very Reverend Dr David Ison says it represents the nation "picking up the baton" from the Queen as a thank you for her years of service.

He says: "We ourselves are committing to how we can make the world a better place and serve others and not ourselves, and if that message gets across to people that will be fantastic."

Dean Ison will be welcoming guests through the Great West Door of St Paul's, before delivering the bidding during the service.

Crowds hoping to get a glimpse of the Royal Family and guests have started to build up outside St Paul's Cathedral.

One man tells the BBC he camped out overnight to get the perfect view.

A woman says she has been at the cathedral since early this morning - "It's wonderful to be here - fabulous atmosphere."

Another woman, who travelled from Northern Ireland, speaking on the Queen's absence from the service, says: "We're disappointed. [But] we totally understand."

News crews from around the world have also gathered outside St Paul's.

Image source, Getty Images

Image source, Getty Images

Image source, Reuters

Aleem Maqbool
Religion editor

As well as commemorating her service to church and country, the event at St Paul’s Cathedral today pays tribute to the Queen’s commitment to foster unity among all people.

Ahead of the service, which he will be attending, chief rabbi Ephraim Mirvis told me it was clear to him through their meetings that the Queen’s interest in the faiths of others went far beyond duty or even curiosity.

"For us, she doesn't act like a politician," he said.

"She has genuine care, genuine interest, and wants the best certainly for our faith and for all faiths."

Rabbi Mirvis said the Queen’s commitment to holocaust memorial in particular had been hugely appreciated by British Jews.

"I saw at first-hand how she relates to the sorrowful times of Jewish past when I accompanied her on a visit to the concentration camp Bergen Belsen," he explained.

"And there I could see the extent of her connection and her concern for the safety of Jews and for our future survival.”

In honour of the Queen’s Platinum Jubilee, Rabbi Mirvis has written a special prayer, external.

Sean Coughlan
Royal correspondent

It will be a deep regret for the Queen to miss her service of thanksgiving at St Paul’s today.

It’s understood she’ll be watching on television from Windsor but she’ll be disappointed not to be there.

The Queen has often spoken of her own strong personal Christian faith and this church service would have been one of the very most important events for the Jubilee weekend.

The themes of duty, public service and personal belief would have all come together.

So it was something of a shock when the news came last night that she wasn’t able to attend - and it might seem a little strange for those at the service in St Paul’s, as it goes ahead without her.

Image source, Gett

Key timings

At 10:50, Great Paul, the largest church bell in the country, will be rung for five minutes, followed by a peel of bells until 11:25.

Then at 11:30, a national service of thanksgiving will be held at St Paul’s Cathedral to give thanks for the Queen's seven decades as monarch.

The service will include bible readings, prayers and hymns, to recognise and give thanks for the Queen’s reign, faith and lifetime of service.

Following the service, the Lord Mayor of London and City of London Corporation will host a reception for members of the Royal Family and the congregation at 12:25 at Guildhall.

Public service theme

The theme of public service is at the heart of today’s event. More than 400 people from all four nations of the UK have been invited in recognition of their contribution to public life at a community and national level – many for their work during the Covid-19 pandemic.

Image source, Reuters

It was a busy day for the royals yesterday, and tens of thousands of people turned out in central London in glorious sunshine to watch the spectacle and try and catch a glimpse of the Queen.

Millions more enjoyed the day in parks and squares across the country.

Here's what happened:

• Platinum Jubilee celebrations began with the traditional Trooping the Colour military parade
• The Queen made two appearance on the balcony at Buckingham Palace, greeting thousands of well-wishers lining the streets
• She appeared alongside other senior royals, where Prince Louis – one of the Queen’s great-grandchildren – had a starring role
• Harry and Meghan kept a low-key presence, with balcony access restricted to “working royals”
• Hours later it was announced the Queen would not attend today's service after experiencing discomfort
• She was well enough though to take part in a beacon lighting ceremony on Thursday evening at Windsor
• Thousands of other beacons were lit across the country and the Commonwealth
• The longest chain of beacons in the UK was along the 73-mile stretch of Hadrian's Wall in the north of England

Although the Queen has had to pull out of the service later this morning, she did last night attend a beacon-lighting ceremony at Windsor Castle.

The monarch illuminated a Commonwealth Globe of Nations, symbolically sending a chain of lights from her Windsor Castle home to Buckingham Palace, where Prince William watched as a sculpture, the Tree of Trees, was bathed in light.

More than 3,500 beacons were also lit up around the UK and the world to mark the Queen's Platinum Jubilee.

As we have been reporting, the Queen is no longer attending today’s service of Thanksgiving at St Paul’s Cathedral after experiencing discomfort while watching Thursday’s military parade at Buckingham Palace.

The palace said the Queen "greatly enjoyed" her birthday parade and flypast in London but "did experience some discomfort".

Prince Charles, the Duchess of Cornwall, the Duke and Duchess of Cambridge and the Duke and Duchess of Sussex will attend.

Image source, Reuters

Four days of celebrations marking the Queen's 70-year reign began yesterday, with pageants, community events, street parties and plenty of pomp.

The 96-year-old monarch appeared twice on the Buckingham Palace balcony, flanked by other senior royals, as they watched the Trooping the Colour military parade and waved at tens of thousands of well-wishers gathered on The Mall.

In the evening, the Queen led the lighting of the principal Jubilee beacon in a special ceremony at Windsor Castle.

First up today is a service of thanksgiving for the Queen’s reign, held at St Paul’s Cathedral and attended by senior royals.

However, hours after yesterday’s military parade, the palace confirmed the monarch herself would not attend today’s service due to ongoing mobility issues.

Stay with us for updates, analysis from our royal correspondents and plenty of pictures.