Some really useful and insightful posts on this thread. Thank you everyone. 
My 11 year old ds was diagnosed with Aspergers (that's what's on the CAMHS paperwork) 5 years ago. I personally now use the term 'High Functioning Autism'.
He's quite severely impaired in relation to social communication (he scored highly for impairment on this section of the ADOS) but because he presents atypically, I often hear people saying 'he's only 'mildly' autistic'. He has a great sense of humour, engages in conversation with people and at his previous school was well liked and described by his teacher as 'charismatic'.
However, like many other dc's with HFA described here, he's constitutionally unable to see other people's POV. This means he feels picked on when he's told off for inappropriate behaviour and comments. And he won't hold back if he thinks someone's getting at him. If someone tells him off, as he sees unjustly, he'll argue with them until the tongue falls out of his mouth. He hasn't sworn at a teacher yet, but he swears like a trooper at home and in the playground if he's antagonised. If another child threatens him or insults him, he'll threaten and insult them back - he has a very sharp tongue, a quick temper and is massive for his age. Not a good combination. The only good side of it is that he wasn't bullied at his primary school (which was a big, tough inner city primary), mainly because other children found him physically and verbally intimidating.
He's had a horrible transition to secondary. Last week he cried and shouted every morning, pleading not to go in. He got his first detention on Friday for arguing with his tutor. When his tutor phoned up to complain about his behaviour it transpired he hadn't read any of the SENCO's information about DS and wasn't aware that he has SN. I suspect that none of his teachers realise. It's shaken my confidence in the school that such a fundamental fuck up could happen early on - that a child who is actually quite severely impaired and has needed lots of support at primary could have his SN go completely unacknowledged on starting secondary, despite visits last term from the primary SENCO and all the paperwork being forwarded.
:-(