Prince Louis steals the show in leaked royal Christmas card photo

A Christmas card sent by Prince William and Kate Middleton has been leaked on Facebook. Photo / Facebook

A photo posted by a royal fan to Facebook reportedly shows the Cambridges' highly anticipated Christmas card for this year.

In the picture, which is said to be addressed to the NHS workers, the Duke and Duchess of Cambridge can be seen smiling while sitting outside, accompanied by their adorable three children, 7-year-old Prince George, Princess Charlotte, 5, and Prince Louis, 2.

The photo has not been officially released by the palace and it is not known where exactly it was taken. However, the Cambridges spent most of their lockdown at Anmer Hall in Norfolk, so that is a likely location for the shot.

A Christmas card sent by Prince William and Kate Middleton has been leaked on Facebook. Photo / Facebook

Royal fans on Facebook agreed that Prince Louis' beaming grin steals the show in the festive card.

Cuddled by his parents, the youngest of the Cambridges appears to be laughing heartedly for the photo.

The card is reportedly addressed "to all the amazing NHS staff" and says: "Wishing you a very Happy Christmas and New Year".

The Cambridges attend a special pantomime performance at London's Palladium Theatre. Photo / AP

Britain's Kate, Duchess of Cambridge, Prince Louis and Princess Charlotte attend a special pantomime performance at London's Palladium Theatre. Photo / AP

The Cambridges stepped out at a pantomime last night, delighting fans in their first red-carpet appearance as a family-of-five.

At the event, Prince William took the opportunity to thank essential workers and said the nation owes them "a debt of gratitude".

"You have given your absolute all this year, and made remarkable sacrifices," he told the audience before the show began.

Earlier in the week, the couple took a three-day train tour of Wales and Scotland to spread Christmas cheer and thank frontline workers there for their hard and dangerous work. However, they received a frosty welcome from leaders in those regions, with one Welsh official saying he would rather "no one was having unnecessary visits" during the coronavirus pandemic.

Britain has Europe's deadliest Covid-19 outbreak, with more than 61,000 reported dead.