I have friends with daughters at Brigidine.
They absolutely love it. They had some difficulties last year, but seem to be weathering the storm and are very optimistic for the future.
One of my friend's daughters is in the junior school (year 4 or 5, I think) and the class size is around 10 (?). I think they work hard to work across year groups with the house system. Anyways, that particular child has loads of friends, so you wouldn't know she was in a small class. The other child is in the senior school and she is flourishing. She is fairly quiet and would never step forward in a bigger school, but now gets involved in every activity. She is also a top academic achiever on course for a sweep of A* in her GCSEs.
The family became quite involved in social activities when the school was having troubles, and now it seems that they are always doing something in the evenings, such as Quiz Nights, cabarets, school concerts.
If you look at national league tables, they have the highest position locally for small schools, and have the highest added value in their LEA.
Let me know if you want to know more and I will ask my friend. I can only imagine that she will be very positive about the school though.
I live within commuting distance of Brigidine but didn't know about it when my DDs were little. It just doesn't seem to get its 'brand' across very well. It is also bang in the middle of an area with the most complex number of educational choices.