Associate
My friend had this exact issue, he called Google and they said common after phone getting old known issue, they just replaced it within 5 days he had a new one, this was a year and a half ago tho. He also factory reset the phone and it was totally hardware related.
Bugger. I thought this may be the case. I'm well out of warranty I'd imagine (coming up on three years) so I doubt Google would do anything, plus, I bought the phone from Carphone Warehouse as I wanted the blue colour
Thanks for confirming what I'd already suspected though. Now I guess I'll have to decide what phone to get next. Been eyeing up the Nokia 7+. Seems a good deal for £250.