Royal experts are predicting a major "surprise” from Princess Kate’s upcoming carol concert

The Princess of Wales has returned to duty following her cancer diagnosis and recovery earlier this year. And as the 42-year-old mother of three scales up her public-facing engagements, there is one in particular that is getting the world talking.

We are of course talking about her annual 'Together at Christmas' carol service, created by Princess Kate herself and broadcast each year on Christmas Eve.

Kensington Palace confirmed the news last week that Princess Kate would be returning to host the annual Westminster Abbey service - marking her fourth year at its helm. And given her challenging year, it is expected to be a more personal event than usual.

"This year’s service provides a moment to reflect upon the importance of love and empathy, and how much we need each other, especially in the most difficult times of our lives," Kensington Palace confirmed of Princess Kate's personal theme choice. "The service will shine a light on individuals from all over the UK who have shown love, kindness and empathy towards others in their communities."

The statement continued: "This year, Her Royal Highness wanted to celebrate the many people supporting those in need - individuals who have inspired, counselled, comforted, and above all else shown that love is the greatest gift we can receive."

According to experts, the Princess of Wales may even have a surprise up her sleeve, with Kate once performing the piano at the service herself. And given the importance of this year's programme, it is thought that we could see a repeat.

"She's been working on ['Together at Christmas'] behind the scenes. I'm predicting a big family turnout," royal expert Katie Nicholl explained recently on The Sun's 'Royal Exclusive' show. And when asked whether Princess Kate could perform, Nicholl didn't rule it out.

"I'm not sure whether she's going to be involved in the performance at all," she explained. "I mean, we've yet to see. The capacity for surprise, never underestimate it."

'Together at Christmas' will be held at Westminster Abbey, London, on Friday 6 December, and broadcast to UK viewers on ITV1 and ITVX on Christmas Eve.

We will continue to update this story.