Oops, now I've done it!
The figures are those reported by the schools themselves for 2015. AnotherNewt - You're right, many of the schools have opted out of submitting their results but they all proclaim them on their websites during August. You should check their 'News' pages. They all give very detailed information, which is manna from heaven for this who like their numbers...
For 2015, there's been a big uptick in results for both DC and W but especially W.
A Levels:
W
A* = 31.5%
A*-A = 70.3%
DC
A* = 32%
A*-A = 62%
GCSE:
W
A* = 56.3%
A*-A = 86.59%
DC
A* = 52.8%
A*-A = 85.8%
As I said, there's not too much in it.
Accepting that many of the top schools will have improved their results compared to 2014, W and DC would both likely move up in rankings to somewhere like c.mid 40s (W) - c.60 (DC) based on their 2015 results.
W's GCSE results are surpsisingly (for me at least) stronger than Trinity (the top academic school in Croydon borough for the past 5 years), the Sutton grammars as well as St Olaves (these schools operate first past the post systems for academic entry and are often an alternative choice for those applying to W and T).
W's A Level results also see it leap above Alleyn's although behind St Olaves and Wilson's (at A*-A only). Clearly this is no guide to the future for any prospective pupils but at least suggests a positive trajectory especially considering the broader academic range of W's intake compared to the grammars in particular.