Bill Turnbull has called for changes to the law surrounding medicinal cannabis after getting high for a tearful TV documentary exploring his fight with cancer.

The veteran broadcaster hopes that when Brexit is dealt with politicians can get on with “constructive” things like loosening the restrictions on medicinal drug use.

Turnbull was filmed smoking cannabis for a new Channel 4 documentary following his attempts to find suitable treatment for his advanced prostate cancer.

Naga to be a BBC Breakfast regular
Bill Turnbull with colleagues Louise Minchin, Naga Munchetty and Charlie Stayt (BBC)

The 63-year-old announced his diagnosis in 2018 and has been taking cannabidiol to tackle his symptoms, and experimented with smoking psychoactive cannabis through a vape for the new programme Bill Turnbull: Staying Alive.

He said through fits of giggles after smoking: “I cannot compose a sentence, I just can’t do it.”

Despite some reservations about cannabis, he has called for greater freedom for medicinal use.

Turnbull said: “I took a little bit from time to time and it was soothing.

“It made me giggle and want to throw up over the director.

“I do think we need to have a proper conversation in this country about the use of cannabis for medicinal purposes, it’s legal for that purpose in more than 20 countries now.

“We should be one of them, it’s been used for medicinal purposes for thousands of years.”

He added: “Once everybody gets past talking about the ‘B’ word constantly in the halls of power, we can start doing more constructive things, so this would be one of them.”

Staying Alive shows a tearful Turnbull revealing the impact of the disease on his family, his work, diet, and relationships with BBC colleagues.

Bill Turnbull on cannabis
Bill Turnbull apologised for his tears (Channel 4/PA)

The former Breakfast host is filmed tearfully embracing Sian Williams, who has also suffered through cancer.

He said of his recurrent tears in the programme: “I’m a bit embarrassed. It’s a bit of a blubberthon, ‘God I’m crying again’.

“It’s a very emotional business, one is because I am on a hormone treatment which does make me spill over, to suppress the testosterone.

“It makes you more likely to cry and crying is a very important thing to do, I think, when under this kind of stress.”

Bill Turnbull: Staying Alive airs on Channel 4 on Thursday, October 24.