The Prince of Wales has revealed his first session as a crisis helpline volunteer for young people was “terrifying”.

William spoke in detail for the first time about his experiences in 2020, saying the conversations had lived with him when he chatted to members of a youth advisory board helping to shape support given to vulnerable teenagers.

The future king visited Mental Health Innovations (MHI) in west London, a charity established by William’s Royal Foundation, to mark its merger last year with The Mix, a digital youth support charity.

Chatting to the board which advises MHI, William said: “I did volunteering for a bit back over Covid, and some of those conversations lived with me for quite a long time afterwards, and you always say to yourself ‘did I give enough, did I do enough, did I find the right answer’?”

The Prince of Wales gestures as he speaks during a visit to Mental Health Innovations in White City, London (Kin Cheung/PA)

After training, William volunteered in 2020 with Shout 85258, a round-the-clock text messaging helpline, developed by his Royal Foundation with offers support via text message to people in personal crisis.

During the chat William was shown a new website for The Mix that goes live later this year and has been streamlined and made user friendly.

He commented: “The resource thing is really important because when you’re in a mental health crisis the last thing you want to do is read more stuff.”

The youth advisory team also showed the prince a proposed online tool to help volunteers provide answers to clients and William admitted about his initial session: “The first one was quite terrifying.”

Before ending his conversation with the young board, he told them: “You guys are going to be the thermometer of the nation.”

During the event at White City in west London, William later chatted on a roof terrace with a group of mental health experts, including Professor Lord Darzi, director of the Institute of Global Health Innovation, Imperial College London.