aka - If you tracked my postings over the last few weeks you would have seen that my views on the subject has evolved
The original plan was to go private only if we weren't allocated a good state school. My son wasn't so we accepted the Habs place. My daughter, on the other hand, was allocated a good state school and only 4 days ago I argued the case with my wife that we got offerred a good state school so why pay £50k plus for the next 5 years?
I then got talking to a few parents whose kids were at High School and Habs Girls and they made the point that yes academically, if my daughter was bright, the exam results at the end of 5 years would be very similar regardless of whether she went private or not but life at the High School and Habs was more than just about academics. That feedback plus the fact that I didn't want to deny my daughter what her brother got simply because she was lucky enough to get allocated a good state school was enough to seal the deal.
All of this is specific to my income. Obviously if money was more of a contraint with us then I would conclude that extras like nicer field trips wasn't worth the financial burden.