Princess Eugenie was overcome with emotion as she paid tribute to the work of her mother Sarah, Duchess of York in a video call to mark the 30th anniversary of the Teenage Cancer Trust.

Eugenie, who is pregnant with her first child, joined her sister Princess Beatrice in heralding the duchess for inspiring them to become involved with the charity.

The trio, who are all honorary patrons of the organisation, held the virtual chat with representatives from the Trust and Jane Sutton, the mother of the late fundraising hero Stephen Sutton.

The duchess has been involved with the charity for three decades and opened its first special hospital unit for young people in 1990.

Eugenie was almost moved to tears as she told her mother: “We’re very honoured to be here, but we wouldn’t be here unless you had educated us in how we give back to people.”

As the princess’s eyes welled up, she waved her hand in front of the camera, and laughed as she told an emotional-looking Sarah: “I’m going to cry. Stop it.”

She added: “Thank you for everything you’ve done, and that you do for the charity, and for us.”

She recalled how the duchess had taken both her and Beatrice to Teenage Cancer Trust units on their 18th birthdays to show them the work of the charity.

Beatrice added: “Mum, everyone on this call has been inspired today by your boundless energy.

“I think you’ve touched each and every single one of us with the mission that you have embraced through Teenage Cancer Trust.”

Beatrice also praised Mrs Sutton who accepted a posthumous award on behalf of her son Stephen, who died in 2014 after raising millions for the Trust as part of his bucket list challenge.

The princess said: “Thank you for doing everything you do to keep Stephen’s memory supported and therefore supporting this fantastic organisation.”

Nineteen-year-old Stephen, who had bowel cancer, set out originally to raise £10,000 for Teenage Cancer Trust, but ended up smashing his target by collecting more than £3 million before his death.

His fundraising total now stands at more than £5.8 million.

Mrs Sutton said: “I miss Stephen every day and I wish he was here to see all that he’s achieved.

“I always used to joke with him about his original £10,000 fundraising target – I’d say ‘Well, you got that wrong didn’t you Stephen!’

“By the time he passed in May 2014, he’d raised £3 million, but now we’re nearing the £6 million mark and his legacy lives on.

“Stephen’s fundraising has changed the lives of teenagers and young people with cancer.

“He wanted every young person to have access to the same support as he’d had throughout his cancer journey.”

The duchess spoke about the impact of the trust, which provides teenagers with cancer with specialist nursing care and support.

She said: “It’s so shocking to think now that back in 1990 there was no specialist care for teenagers and young adults with cancer.

“Imagine being diagnosed with cancer at 17 and being treated on a ward with much older people, talked to as an adult by doctors when you are still a child, your loved ones not being able to stay with you overnight. How lonely and frightening that experience would be.”

She praised the charity’s founders, Dr Adrian Whiteson and Myrna Whiteson, saying: “What an incredible difference this charity has made in such a short space of time.”

Also on the call was The Who’s Roger Daltrey, who is also a patron and has been the driving force behind the charity’s well known gigs at the Royal Albert Hall over the decades.

He described how his own unhappy teenage years led him to help young people with cancer.

Daltrey said: “This charity has given me so much back.

“My teenage years were very, very difficult as I’m sure maybe yours were too.

“I call that my Tommy period in life, and isolation was quite a big part of it, I didn’t quite know who I was.”

He added of when he found out about the trust: “A kind of lightbulb went on. I promised Adrian that when The Who got back together, we would do some shows, which we did, and it all took off from there.”

Donations to Teenage Cancer Trust can be made at www.teenagecancertrust.org