It's an interesting situation to look into.
When dd1 was first at juniors we were staggered by the amount we were expected to spend.
Not only did we have to provide all writing stuff excluding the paper, but we'd get two or three little notes along the lines of "to do the craft/science/project/ict/sports etc. this term we need from each parent." each month.
The list of stationary stuff we were expected to provide was two columns on A4 paper-and they still asked for donations towards more stuff. Stuff they asked for would be specific too-like the Bic handwriting pens, or a specific type of calculator.
I added up in the first term how much I'd spent and it was well over 100.
Some parents reckoned it was a way of "covert selection" as it was found that some parents were not choosing that school simply on the amount of money it cost. And that it was a deliberate way of putting people who were less well off away from the school.
However, a new head came in, he took totally away the little letters (well, we might get 1-2 a year for a group coming into school at no more than 5, and considered to be voluntary) and has reduced the stationary list to about 6 things and colouring crayons optional.
However the school is now much more massively popular, probably about half as many applicants again (and it's large, so that's a significant number).
However I'd say the "middle class" element if anything has increased significantly, simply because the catchment has decreased and it's position is in the middle of large substantial properties. The "cheaper" estate at the other end of town now stands no chance of getting in should they want to.
So was the excess charging a deliberate attempt to put people off? I suspect not. However if it was, then it was nothing like as successful as making the school much more popular.
And in all honesty, I don't think many people would have chosen to go all the way across town to another junior school, a few perhaps, but despite the school on the other estate being failing since we moved here nearly 15 years ago, I have known several people choose to change to that school when they've moved into the estate simply because the hassle of getting there.
However the difference now is that if someone moves out of that estate then they can't usually get into the juniors here because the waiting list is huge, before the school became so popular there were usually spaces in each year.