It is nigh on impossible to evict ASBO HA tenants.
I once made the mistake of asking a guy to pick up his dog's poo that he had left directly in front of my house. Cue 'stupid cunt', this is the street cleaner's job, mind my own business, etc.
I had a pretty good hunch that it was HA, looked it up on land registry (I was correct), made a complaint to the HA. As it happens, it's a breach of his tenancy to have a dog because he doesn't have a garden. The HA inspector showed up unannounced, saw the dog, ordered him to get rid of the dog to retain the tenancy.
A few weeks later, he showed up at my door, calling me a filthy cunt for grassing him up yada yada, threatening to kill me, etc. I have CCTV, it was a pretty easy case to make. He was arrested for harassment (I think), easily convicted and ordered into anger management courses to retain the tenancy (at the council's expense, naturally).
He's still in his flat, still calls me a filthy cunt when he sees me, still has the dog, still doesn't pick up after the dog.