Those are really good levels of attainment for a 4/5 year old. Was it all learned at school, or did you do some work at home?
I'd have thought it hugely unlikely that a KS1 teacher would be able to cater for a child working at year 5 or 6 level.
If you think about it, it would mean a one-to-one lesson one day to teach them co-ordinates in maths whilst simultaneously teaching the rest of the class to add numbers up to 20. Similarly, teaching the child all the different methods of multiplication and division (because they aren't allowed to just master one and move on). Then they'd have to see evidence that the child had mastered it. Same with geometry etc.
As to English, they'd need to have done the lessons about using quotation marks. Ditto the other punctuation and grammar lessons. Then, they would need a level of life experience to be able to answer the reading comprehension questions.
I believe that its hard enough to get sufficient help ("intervention") if your child sits at the other end of the ability spectrum.
IME, the words you will start saying over and over again are challenge, extend, enhance.
Progressing through these levels is all about independently demonstrating the skill on separate occasions and in different ways. If your child isn't given the chance to show that they can plot co-ordinates and reflect a shape through a point, then the official record will show that they do not know it.