We looked at Dartford girls last year and I was really impressed with it. Unfortunately from where we live our DD would need to do exceptionally well to get in. Apparently this school is difficult to get in to if one doesn't live close, therefore I don't think this would be a realistic choice for us.
As far as Townley is concerned, we didn't look at this school. I'm sure it is a very nice school but I don't like it's location. (Broadway Shopping Centre). I know a few people who have children at Townley and they complain about peer pressure to hang out at the shopping centre after school. I'm not sure how big a problem this really is but I don't think it is for us.
As far as GCSE results are concerned, I'm not worried about the tables. I think the league tables can be deceptive. For example if you look at the difference between C&S and BGS there is only 2 or 3 % between them according to the A-C tables, however I saw tables published based on the number of A* AND A's published and there was a significant difference between the 2 schools.