Thank you everybody, some really interesting comments there!
I think I charged in in my usual bull in a china shop approach without doing any research
I am definitely going to get some of the Bond assessment papers, I actually looked at them in town yesterday and had put a note in my son's contact book asking what his teacher thinks.
I have been in touch with a tutor for him as well, (waiting for a call back to see if she has space) but not specifically for 11+ stuff, just to boost his confidence on a 1:1 and hopefully give him some structure to his studying. (having seen the result or a lack of structure with my almost 15 year old!)
It was reassuring to read that the NVR paper was meant to be hard as I must confess I tried it and it made my head hurt!