If you search for previous threads I've started, there are any number of them about DS (5) who is behind with reading - he's August born which may be relevant, but has never shown any interest in reading.
On Wednesday DS mentioned he'd left PE to do reading with Mrs X (a support worker for children who need extra support) and then on Thursday DH was with him in the queue waiting to go into school when Mrs X came over and took DS out of the queue to go off and work with her. After school DH asked DS how many children are spending time with Mrs X. The answer - two. DS and the child whose first language isn't English and who uses a non-European alphabet at home. 
At parents' evening last term, DS's teacher said that he was on a table with a teaching assistant for the 4 children, but that he was the most able in that group. He's also recently done a piece of writing that was so good the teacher took him out of class to find the headmaster to tell him how impressed she was by it. But his homework over the weekend was nearly illegible, and parents at drop-off this morning were handed a performance report for their children: DS is the bottom at everything and failing to make any progress - reading, writing, speech and listening, everything. At home, he is a happy, chatty boy with a good vocabulary but the teacher has said that she never sees that side of him at school, he just seems to sit back from proceedings so he doesn't actively engage with the other children although there are children who want to play with him.
We have 3 schools in driving range, but we'd only have pre-school childcare for this school (another mum drops him off for me a couple of days a week) and I work FT so we can't look at HE and can't afford somewhere like Montessori where they don't focus on reading / writing below are 6.
The school seems fine, it's just that it's not working for DS. What the hell do we do? We've been reading to since he was a tiny baby, we make sure we do different activities with him at weekends, go to the canal, museums etc. he's not always in front of the TV, and he seems no different from the other children, but he's just not getting this.