It's just as plausible that Turing was lying to his friend about his real state of mind
It's also plausible that he wasn't lying, but actually felt more cheerful having made the decision to end his life. This is also not unheard of.
Still, Copeland makes an interesting case. I'm inclined to agree -- the fact that Turing had cyanide in his house, ostensibly for purposes other than suicide, makes accident seem at least equally plausible.
He was also a classic example of a British eccentric inventor, at one point he fashioned his own mercury delay lines for digital storage.
I have no trouble at all with the notion that he (foolishly) had a small unventilated room with cyanide, mercury, bismuth, probably a small kiln furnace for metal casting, floor to ceiling racks of odds and ends and semi regular small explosions and benchtop melt downs.
It's a lifestyle that's accidentally killed more than one person and it could very well have claimed Turing.
It's also plausible that he wasn't lying, but actually felt more cheerful having made the decision to end his life. This is also not unheard of.
Still, Copeland makes an interesting case. I'm inclined to agree -- the fact that Turing had cyanide in his house, ostensibly for purposes other than suicide, makes accident seem at least equally plausible.
It's tragic either way, of course.