Sorry for the delay. To answer some questions:
"How do you know what the next term's activities are, and how do you know that he already knows it all? Have you seen his books and is it apparent to you that he really is doing everything easily? What level is his homework - is it challenging? If you have enough evidence (based on these sorts of questions) to conclude that the work he is being offered really is too easy"
Well, the school tells us their teaching aims and topics for the next term and he knows them all already because we asked him and he answered correctly.
He tells us that the work is too easy. They give them a printed sheet with one line on it and ask them to write a sentence about it. I ask him why he doesn't write more and he says "because we are only allowed one sheet and it only has one line on it".
They don't get (and never have had) any homework, so I can't assess it. He sets his own homework - with our help (like writing books, comics and poems, or learning his times tables)
"I'm sorry, I can't imagine how a 7 year old can 'learn nothing from his teachers'. I would love clarification about this from the OP."
There are some classes that he finds particularly boring, such as one class on Tuesday morning where they do cutting out and playdough. Sometimes they do handwriting skills, but he is not allowed to do joined up hand writing, even though his hand writing is better than mine!
I am sure he learns stuff from them, but my point is, they are not stretching and differentiating sufficiently.
"I agree, friendly. I don't really get the 'stretching' at 7. There are so many fun things going on in primary schools, that I really don't see how a child gets bored!"
Why don't you get stretching at 7? I define "stretching" as part of "good teaching". Know the abilities of your students and give them work to excite them about learning. This is the same for a 7 year old as it is for a 15 year old. Surely exciting kids about learning is the primary aim for a teacher in primary school.
Fundamentally, my opinion is clouded by my own personal experiance. When I was at primary school, I was 2 years ahead in maths and science and was taught things like trigonometry when I was in year 5 and 6. Then when I went to secondary school I didn't learn anything new in maths until I reached O Levels. By this time I had dis-engaged and forgotten how to self learn. This meant that my O Level grades were quite poor, and this read accross to my A Level and degree achievements. A lack of stretching at school stopped me from achieving my full potential, and I don't want this to happen to my DCs!
I don't believe this is unreasonable, since we all pay quite a lot of tax!
P.S. This is not an attach on teachers, 'cos I think much of the problem is the bullshit OFSTED tickbox teaching that they are forced to undertake.