I honestly don't think it was a hairball, he actually did not even try to vomit anything up, i have never seen his mouth quivering like that, it was more like something stuck alright or an allergic reaction and it was straight after eating the cat food, immediately in fact.

Ash is my old grey boy, he was named by my then young daughter after Ash on pokemon, and of course he just happens to be that colour too lol.