Hi Ticker, thanks for your help and thanks for telling me who I should see to rule in or out tourettes.
He has been diagnosed with high functioning autism which fits in with aspergers (that is his exact diagnosis) not really a very clear one for us or for him. I think they know he is autistic, but he has always been, and still is a very difficult child to pin down to one diagnosis. My husbands half sister though does have a son with Aspergers, so autism is a genetic factor in our family, or so it would seem.
When I think back he has been making strange noises (mostly throat clearing since he was about 2), it stopped for about a year or so and then he went back to the throat clearing and has been doing it ever since, just lately it is this different noise, and very constant and loud.
I will phone my gp tomorrow or my HV to see if they can refer me on to a neurologist, I really appreciate your help.