Prince William, Kate and Prince Harry attend Heads Together Christmas party

By Ainhoa Barcelona

Prince William, Kate and Prince Harry made up for the fact that they won't be spending Christmas Day together by attending a charity party on Monday morning (Dec. 19) as a trio. Celebrating the hard work of volunteers involved in their Heads Together charity, the royals were the guests of honour at the organization's Christmas party.

Kate looked party ready in a festive red dress by Vanessa Seward, while William and Harry went smart casual in shirts and suits.

The royal brothers each joined a group breakout session where counsellors and volunteers shared knowledge and training on dealing with a range of issues, including homelessness.

Meanwhile Kate, 34, joined a live online chat about counselling with volunteers and young people from around the UK.

The party was hosted by youth support service The Mix, one of the eight charities involved in the royals' mental health campaign, Heads Together. William, Kate and Harry had the opportunity to speak to volunteers from The Mix, and heard about their personal experience of online and telephone counselling support.

At the Christmas party reception, the royals also kicked off The Mix Annual Awards by presenting the Volunteer of the Year Award.

TAP TO VIEW GALLERYA photograph of Kate Middleton wearing a red and green Vanessa Seward dressKate looked festive in a Vanessa Seward dress

On Tuesday the royals will again step out for the traditional Christmas lunch at Buckingham Palace hosted by the Queen. It will be a chance for all of the family to catch up before the monarch retreats to Sandringham Estate in Norfolk for the Christmas period. She will be joined by close members of the royal family, including Prince Charles and Prince Harry.

This year however, Prince William and Kate will spend Christmas Day with Kate's side of the family, the Middletons, in Berkshire. The Cambridges usually mark Christmas with the royals at Sandringham, but this will be the second time they celebrate with the Middletons since they married in 2011.

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