My dd1 is in reception at a 90 intake school, not in Ealing though. She doesn't seem to find the numbers intimidating, but she does spend the vast majority of the time with the 30 children in her class. I think it depends how the school is set up. Our 3 reception classes are pretty self-contained from the rest of the school, with their own outside play areas, toilets etc. She had to stand up in assembly recently which she said was scary as there were so many people looking at her (just infants though so 270 children).
It is quite chaotic at drop off and pick up time with over 600 parents (infants and juniors), younger siblings, pushchairs, scooters, dogs etc, but I seem to notice that more than dd!
I do also feel dd is a bit anonymous in class as she is quietly capable and just gets on with things. I think she may be better suited to a smaller class size, on the other hand she has lots of lovely friends, and who knows, in a smaller class she may not have "gelled" with anyone....
If I had my way she'd be in a lovely little school, with more individual attention, but not possible around here unless you are prepared to pay for it!