Kate Middleton went to therapy with her siblings Pippa and James

Sunday 10 October marks World Mental Health Day.

The Middleton siblings, Kate, Pippa and James, are famously close-knit.

So close, in fact, that James, who recently wed his partner Alizée Thevenet in the South of France, has opened up about the support system his older sisters have provided for him during previous periods of poor mental health.

James's oldest sister, the Duchess of Cambridge, has championed more open discussion about mental health in her role as a senior working royal. And it'd appear that the cause is just as important to the duchess in her personal life as it is in her professional one – as James revealed that Kate and Pippa accompanied him to therapy while he was battling depression.

In an interview with The Telegraph in 2018, which has recently resurfaced ahead of World Mental Health Day on 10 October, James reflected on a period in which he was experiencing suicidal thoughts.

"I couldn't do anything," he told the publication. "I couldn't sleep, read a book, watch a film eat. If I ate something it just sat there. I was just like, 'What am I meant to do?' I was better off in my own company , so I didn't have the additional worry of someone thinking, 'What's wrong with him?' I removed myself from everything."

The entrepreneur admitted that despite his close relationship to his family, including parents Michael and Carole Middleton, he initially found it difficult to speak to them about how he was struggling to cope.

During a year-long course of Cognitive Behavioural Therapy (CBT), however, James said that his whole family attended therapy with him – something that proved hugely helpful in his recovery.

"That was actually a very, very big thing," he said. When specifically asked whether Kate accompanied him to sessions, he confirmed.

"All of them," he told the publication. "Not necessarily at the same time, but either individually and sometimes together. And that was so important because that helped them understand me and how my mind was working. And I think the way the therapy helped me was that I didn’t need my family to say, 'What can we do?' The only thing they could do was just come to some of the therapy sessions to start to understand."

James added that his family are overjoyed at how much progress he has made.

"They've seen me where I was and to see me now...," he said. "It was a dark and miserable place to be, but the fact is there is hope at the end. It requires effort and energy, but the grass can be greener than it was before."

If you or someone you know is struggling to cope, you can freephone Samaritans for confidential support 24 hours a day on 116 123 or email jo@samaritans.org.