Prince William, Kate Middleton 'going through hell' during cancer treatment, says clothes designer

The Prince and Princess of Wales are "going through hell" as Kate Middleton undergoes preventative chemotherapy for cancer, according to a report.

Amaia Arrieta, who designs the clothes worn by their children Louis, Charlotte and George, told the Telegraph newspaper she was heavily impacted by Kate's diagnosis.

"I'm heartbroken at the moment, I think they are going through hell," she said. 

"I hope they will be back. It's really personal."

Arrieta provided some of the clothing worn in the infamous Mother's Day picture taken by Kate that caused a furore over its undeclared digital editing.

She didn't cite any sources for comments that the royal couple had made over their diagnosis.

In public, William has recently said that he and the family are "doing well" just six days ago.

During the Prince of Wales' April 30 appearance at the James Place Newcastle grand opening in the UK, he was asked by a member of the crowd how they were coping and he told them: "All doing well, thank you. We're all doing well."

Earlier in April, royal author and former BBC correspondent Jennie Bond told Bella magazine in the UK the Princess of Wales "says she's getting stronger every day so I'm sure she's doing her best to join in the outdoor life - the picnic, barbecues and walks on the beach".

She also claimed the support of her husband Prince William had been "crucial" to her recovery.

However, she cited no official sources to back up her claim the Princess was in good health.

Bond's comments came after a video was released to the public in March month which revealed Kate was undergoing preventative chemotherapy treatment for cancer, which was discovered during her "planned abdominal surgery" in January.