A documentary following a rugby player who suffered a stroke and woke up gay is to air on BBC3 tonight.

Chris Birch, now 27, was a Welsh bank employee who weighed 19 stone and enjoyed heavy drinking sessions.

Following a stroke in 2011, he is now a Welsh hairdresser with sweeping dyed hair and a male fiancé.

I Woke up Gay will examine how Birch’s personality changed so abruptly.

He tells the BBC: “I was doing a forward roll down a grass bank one day and cut off the blood supply to my brain which caused a stroke to happen. It was from there, while I was recovering, that I realised I’d changed.

“The Chris I knew had gone and a new Chris sort of came along. I came to the realisation that the stroke had turned me gay.”

He describes a lonely period after the realisation that he was gay but said he was ultimately “happier now than I ever have been”.

He says: “You’re afraid to tell people, you’re afraid to have that conversation or even talk about the possibility that I have even changed in some way, and I suppose I dealt with it by moving out of my family home by myself and having to realise who I was all over again.”

Given the rarity of strokes causing such marked personal changes, some, including Birch’s partner, believe he was always latently gay.

Birch’s partner Jak says: “I’ve still got the same opinion that it was just something that was always there.

“People grow up not knowing they are gay and have families and then they realise they are gay, but they don’t have a stroke to realise that.”

The documentary I Woke Up Gay will air on BBC3 tonight at 9pm, BST.