The Duke and Duchess of Sussex have bid au revoir, if not goodbye, to formal royal life after carrying out their final public engagement in the UK as senior working members of the royal family.

Harry and Meghan attended the Commonwealth Day service at Westminster Abbey on Monday – their first appearance alongside senior family members since their shock announcement in January that they would be stepping back from official duties.

Unlike last year, when the Sussexes took part in the Queen’s formal procession through the nave of the abbey, this time they were ushered to their seats ahead of her entrance.

In an 11th-hour change of plan, William and Kate also did not join the Queen’s procession, although they had been due to according to the order of service, which was signed off and printed before the decision to change was made on Sunday. Buckingham Palace offered no explanation for the switch.

All eyes were on the Sussexes as they joined the Queen, Prince Charles, the Duchess of Cornwall, the Duke and Duchess of Cambridge and the Earl and Countess of Wessex for the celebration. From 31 March, they will retain but not use their HRH styles and live mainly in North America as they pursue their ambition to become financially independent.

Harry, who colour-coordinated his jacket lining to match his wife’s emerald green Emilia Wickstead dress, looked solemn and pensive at times during the hour-long service.

Facebook Twitter Pinterest The couple leave the service, following the senior royals out of Westminster Abbey. Photograph: Reuters

Meghan, who married into the royal family less than two years ago, smiled broadly and curtsied to the Queen and Charles from the couple’s second-row seats at the high altar. She gave a small wave to William and Kate as the Cambridges took up their seats in front.

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Coronavirus meant handshakes were not exchanged at the abbey. The Queen resorted to head bows, while Charles adopted a “namaste” pose with his palms pressed together.

As the Sussexes left the service, Harry elbow-bumped Craig David, and Meghan hugged Alexandra Burke after both singers had performed.

The couple stopped to congratulate Anthony Joshua, the two-time heavyweight boxing world champion, on his eloquent address reflecting on being a “child of the Commonwealth” and his British and Nigerian heritage.

Joshua had told the congregation: “Like me, so many children of the Commonwealth have two homes and two identities, two cultures and two ways of viewing the world. Some have more than two.

“These days we hear so much about division and difference that some might be tempted to see that as a bad thing. But, on the contrary, it’s a beautiful thing, a thing to be celebrated and cherish, and a great source of peace and stability.”

Facebook Twitter Pinterest The Duchess of Sussex speaks to the British boxer Anthony Joshua as she leaves the service. Photograph: Reuters

His words seemed to resonate with Meghan, the first biracial member of the royal family, who later engaged in animated conversation with the boxer.

She and Harry then got into their car, which whisked them off to their uncertain future. It is not known when they will next appear in public in the UK. They are said to be “positive and excited” about carving new roles, and are expected to announce news of their plans in the near future.

Boris Johnson and his pregnant fiancee, Carrie Symonds, were among a congregation of senior politicians, high commissioners, ambassadors, faith leaders and schoolchildren.

One notable absentee was the Duke of York, who has stepped down from public life after the fallout from his TV interview on his friendship with the disgraced financier Jeffrey Epstein.

The Queen’s decision to invite the Sussexes is said to have been very important to them. Although they are unable to formally represent the Queen, and will not play as large a role in the Commonwealth as she might have hoped, they will still be involved through charity work. They remain the president and vice-president of the Queen’s Commonwealth Trust, which supports young global leaders.