when i worked it barnet it was very hard to get into and they more interested in results that in the actual boys. e.g. you had to be predicted an A at gcse and get an A to be able to go on and do the subject at A level. So even if you got an A at gcse maths if you were predicited a "b" you would not be allowed to do A level maths. Hope this makes sense. Mind you that was 5 years ago so hopefully things have moved on.
Do they still do selection tests? Boys used to get in from many many miles away whereas the kids I taught who lived just up the road did not stand a chance.
Have they got a new pool yet?
Did good productions (e.g. Sweeney Todd) when i was around.