Kate Middleton, Prince William and Prince Harry join Queen Elizabeth at Westminster Abbey

Royal day out! Kate Middleton and Prince William arrived at the annual Commonwealth service at Westminster Abbey on Monday to support his grandmother Queen Elizabeth. The two were joined by other members of the royal family including Prince Philip, Prince Andrew and Prince Harry, who was enjoying some family time before jetting off to Nepal this weekend.

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Kate, William and Harry arrived at the Commonwealth service to support The Queen Photo: Getty Images

The royals gathered to celebrate the service, traditionally held on the second Monday of March every year, to recognize the 53 countries and its people that make up the Commonwealth.

While the day was all about family, Kate, 34, showed off her flawless fashion. In an Erdem coat and a John Boyd hat, Kate arrived arm-in-arm with William, 33, who opted to leave their children Prince George and Princess Charlotteat home during the engagement.

Kate stunned in Erdem during the ceremony Photo: Getty Images

As head of the Commonwealth, all eyes were naturally on the Queen. Her Commonwealth Day Message was broadcast throughout the Abbey and later to all of the Commonwealth Nations. The theme of her speech this year was "An Inclusive Commonwealth" – underlining the diversity of the Commonwealth, which is made up of more than two billion people.

The monarch, who turns 90 next month, said that an essential ingredient of belonging to the Commonwealth was "the willingness to share, to exchange and to act for the common good". "By including others, drawing on collective insights, knowledge and resources, and thinking and working together, we lay the foundations of a harmonious and progressive society," she added.

The Queen used the occasion to celebrate diversity Photo: Getty Images

Apart from the Queen's speech, the hour-long service, which is the biggest multi-faith celebration in the UK, featured a mix of testimonies, readings, hymns and musical performances.

This year Prince Harry's good friend Ellie Goulding, who performed at William and Kate's wedding in 2011, lent her voice to the ceremony and sang Fields of Gold. Former UN secretary general Kofi Annan also gave a speech.

Among the guests in attendance were politicians including Prime Minister David Cameron and Nigel Farage, High Commissioners and Commonwealth dignitaries.

After the service the Queen will lead her family to walk by the Commonwealth Flags, where well-wishers will present them with bunches of flowers.William, Kate and Harry will then attend a reception in the Dean's Yard and later the Queen and Prince Philip will attend an evening reception at Marlborough House.

Prince Charles and his wife the Duchess of Cornwalldid not attend Monday's service, as they are on a five-day tour of the Western Balkans, visiting Croatia, Serbia, Montenegro and Kosovo.

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