This is Charcoal: a London pigeon who contracted Paramyxovirus.
Looking very well here, he was never going to survive by himself.
His neck became severely twisted backwards by the disease, and he would think up was down, and down was up.
I rescued him several times from neighbours' gardens after he took off from the roof and slammed into the ground, upside down.
He finally recovered fully, and the last time I saw him, he was accompanied by a pure white pigeon, who must have stolen his heart.