Britain's Prince William took his oldest son, Prince George, to a homelessness charity in London where the pair helped make Christmas lunch for people in need, Kensington Palace said on Saturday.

The visit was particularly poignant for William, heir to the throne, because his late mother Princess Diana had taken him to the same charity when he was 11 years old, an experience which inspired him to set up a programme aimed at ending homelessness.

During the trip to the charity's centre, named The Passage, George signed the visitor's book on the same page previously signed by Diana, who was killed in a car crash in Paris in 1997 when William was 15 years old.

Wearing aprons, George, 12, and his father worked in the kitchen, placing food in baking trays, while they talked and laughed with the centre's catering staff, before heading out to lay long tables with napkins and Christmas crackers.

"It was important to The Prince of Wales to share with Prince George the work of The Passage and to spend time volunteering alongside the team," a spokesperson for Kensington Palace said.

"They both greatly enjoyed meeting staff, volunteers and service users as well as learning more about the charity’s work."

As well as working to try to stop people becoming homeless, William also champions environmental causes and campaigns for more openness about mental health issues.

William, his wife Kate and their three children are expected to spend Christmas at King Charles' Sandringham estate in eastern England.