We were in the same position almost 2 years ago. We did not live in Orpington nor Barnet at the time so were prepared to move. We knew nothing about these school before so it was hard to make a decision. I'd like to tell you how we came up with our choice if it helps you.
- Academically: both are very good. I personally think there's not much difference between top 10 (state schools, can't afford private). Moreover, best school does not guarantee best student. Good teachers help, but also depends on individual's effort. Best schools can not guarantee good teachers or good pastoral care for the whole of 7 years. Every school has its own strengths and weaknesses, and things can all change. But the one thing you can have some control of is your son's commitment to work hard.
- Financially: houses in Orpington seem a bit more affordable than in Barnet. The area has lot of green space. Commute into LD is just 15' fast train.
- Family wise: lots of family and friends live in the south
My son chose St. Olave's because he was impressed with the Open day and some of his friends also got places there. I think we'd also be happy if he chose QE (and if we could afford a house in Barnet