EXCLUSIVEKate Middleton's secret trip to cancer hospital before Christmas: How Princess of Wales returned to thank nursing staff in private festive visit

Her return to the Royal Marsden this week to meet fellow cancer sufferers and thank nursing staff was as moving as it was surprising.

The Princess of Wales undertook her first solo public engagement on Tuesday in more than a year as she visited the London hospital where she has secretly undergone her own chemotherapy treatment.

But the Mail can today reveal that it was not the first time that Catherine, 43, has returned to express her heartfelt thanks to the team who, as she so eloquently put it, ‘have walked quietly alongside William and me as we have navigated everything’.

In fact, she secretly popped in to the specialist cancer care centre just before Christmas during an ‘under the radar’ festive visit, it can now be disclosed.

She was quietly taken through a back entrance at the hospital to avoid being spotted, just like she did during her treatment.

And it is understood she also brought the doctors and nurses hand-picked festive gifts and treats, including biscuits, as a sign of her thanks.

The Princess of Wales undertook her first solo public engagement on Tuesday in more than a year as she visited the London hospital where she has secretly undergone her own chemotherapy treatment

The Princess of Wales undertook her first solo public engagement on Tuesday in more than a year as she visited the London hospital where she has secretly undergone her own chemotherapy treatment

The Princess of Wales hugs Rebecca Mendelhson during a visit to the Royal Marsden Hospital

The Princess of Wales hugs Rebecca Mendelhson during a visit to the Royal Marsden Hospital

It was not the first time that Catherine, 43, has returned to express her heartfelt thanks to the team. Pictured: Talking with Peter Burton

It was not the first time that Catherine, 43, has returned to express her heartfelt thanks to the team. Pictured: Talking with Peter Burton

A source described the gesture as ‘typically thoughtful’ of Catherine - and yet another indication of how incredibly appreciative she is of all the team have done for her over the past 12 months.

It is not clear how long she spent with them during the strictly private visit, which was not recorded in the Court Circular, the official record of royal engagements.

The last time she was there as a patient was before the autumn, when she joyously announced that she had complemented her course of preventative chemotherapy for an undisclosed form of the disease.

It was discovered after she underwent serious abdominal surgery in January.

This week the princess told fellow patients that she was ‘so grateful for all the care and support I’ve received here’.

She later revealed in a social media post that she was now officially in remission, which means that doctors can find no further evidence at the moment that cancer is present.

It is understood she chose to make the announcement separately because she felt it would have been inappropriate to impart the news while she was with patients who are still undergoing treatment and possibly struggling with the enormity of their own diagnosis.

It was also announced that she had become joint patron of the hospital in London’s Chelsea, along with her husband, who was already president.

Catherine secretly popped in to the specialist cancer care centre just before Christmas during an ¿under the radar¿ festive visit. Pictured: Talking with Katherine Field

Catherine secretly popped in to the specialist cancer care centre just before Christmas during an ‘under the radar’ festive visit. Pictured: Talking with Katherine Field

It is understood she also brought the doctors and nurses hand-picked festive gifts and treats, including biscuits, as a sign of her thanks. Pictured: Hugging Rebecca Mendelhson

It is understood she also brought the doctors and nurses hand-picked festive gifts and treats, including biscuits, as a sign of her thanks. Pictured: Hugging Rebecca Mendelhson

A source described the gesture as ¿typically thoughtful¿ of Catherine - and yet another indication of how incredibly appreciative she is of all the team have done for her over the past 12 months

A source described the gesture as ‘typically thoughtful’ of Catherine - and yet another indication of how incredibly appreciative she is of all the team have done for her over the past 12 months

It is understood the position will see her continue to visit the hospital regularly both publicly and privately, offering her support to other patients and the nursing team.

‘This is a lifelong commitment,’ a source said.

One of the aspects the princess is keen to help on is how to offer cancer patients and their families the best possible wrap-around support for their physical and emotional wellbeing, both during the dark days of their initial diagnosis and treatment, but also in coping with long term side effects and holistic care.

The princess has herself made clear that there will be no immediate return to royal duties for her.

Instead she intends to continue to focus on her recovery while gradually building up her diary in the coming months.

She has spoken openly of the devastating effect of her diagnosis and cancer journey on both herself and her family, while Prince William has described the last year as ‘brutal’ and the worst of his life, but recently paid tribute to his wife’s strength throughout.