The royal family were united in celebration of the Queen at her Service of Thanksgiving as the Duke and Duchess of Sussex publicly joined relatives for the first time since quitting official duties.

The Queen was missing from the gathering but the Duchess of Cambridge said later she had enjoyed Thursday’s historic Platinum Jubilee celebrations but the day had been “very tiring”.

Harry and Meghan were the focus of attention in the absence of the monarch and the couple, after their decision to step down as working royals for financial freedom, were relegated to a second row seat in St Paul’s Cathedral.

The 96-year-old Queen watched the service on television from Windsor Castle after she suffered “discomfort” following a busy first day of festivities including a double balcony appearance and a beacon lighting.

Buckingham Palace later confirmed the Queen, a passionate horse owner and breeder, would not be attending the Epsom Derby on Saturday.

The monarch, who has been experiencing episodic mobility problems, was not expected to be in the royal box for the major sporting event and is likely to watch it on television at Windsor Castle.

The Princess Royal is now expected to join racegoers at the Epsom racecourse.

During the service there were smiles from the royals and ripples of laughter from the congregation as the Archbishop of York compared the monarch’s well-known love of horse racing to her long reign, suggesting it “reflects the distance of Aintree more than the sprints of Epsom”.

In his sermon the Most Rev Stephen Cottrell said the Queen was “still in the saddle”, as he thanked her for “staying the course”, with her granddaughter Olympic equestrian Zara Tindall smiling at the remarks along with the Earl and Countess of Wessex.

The Service of Thanksgiving saw more than 400 hundred people who have served the nation, many during the pandemic, invited to be part of the celebrations marking the Queen’s 70-year reign.

They were among a 2,000-strong congregation which included the Prime Minister Boris Johnson, who was booed by the crowd outside, Cabinet ministers, Labour leader Sir Keir Starmer, first ministers of the devolved governments and every living former prime minister.

It was the first time Harry and Meghan had been on full public view alongside the Windsors in two years and when they arrived were greeted by cheers, responding with smiles and a wave, but both boos and cheers could be heard as they departed.

Indicative of their more-minor position within the royal family, the couple had taken their second-row seats with Princesses Beatrice and Eugenie and their husbands, and Lady Sarah Chatto and her family, before the Prince of Wales, Duchess of Cornwall and Duke and Duchess of Cambridge arrived.

There appeared to be no opportunity for the Sussexes to meet the senior royals during the service, and afterwards, following seniority, Charles and Camilla and William and Kate left first before Harry and Meghan.

Royal horsewoman the Princess Royal nodded in approval as the Archbishop suggested the Queen’s long reign had “certainly, less dressage than most people imagine”.

“With endurance, through times of change and challenge, joy and sorrow, you continue to offer yourself in the service of our country and the commonwealth,” he said in his sermon.

“Your Majesty, we’re sorry you’re not with us this morning, but we are so glad you are still in the saddle. And we are all glad that there is still more to come.”

As they left Meghan, dressed in an elegant trench coat from the Dior Haute Couture spring-summer 2022 collection by Maria Grazia Chiuri, a Stephen Jones hat and wearing white gloves, held hands with her husband who bit his lip at times.

Kate spoke about the Queen when she chatted to Gill Smallwood, chief executive of domestic violence charity Fortalice, during a Guildhall reception after the service.

Ms Smallwood told the PA news agency: “She (Kate) said, ‘yes, she was fine, it was just very tiring yesterday, and she (the Queen) had had a lovely, lovely time’.”

Before confirmation was given the Queen would not attend the Derby, her hopes of having a winner at Epsom were ended when her horse Just Fine was withdrawn from the World Pool Northern Dancer Handicap.

Phil White, London regional director for The Jockey Club, said: “We would like to wish Her Majesty the Queen a wonderful Platinum Jubilee. It is a rare occasion that The Queen is unable to join us at Epsom Downs but we are delighted she plans to enjoy Derby Day on television.”