@Powderherface I have no idea. There are lots of through schools though with junior departments in London and the intake is typically in my experience 1/3 to 1/2 of year 7.
The numbers are crazy but in reality I think the approach parents are taking means that pretty much every school (even the most popular) have to over offer quite substantially. For example, irrespective of where people live, Kings, SPJ and Westminster seem to have the same parents applying to them and the same strong candidates will get offers from all 3. All of them, probably need to offer at least double the places they have knowing that they'll probably be turned down by large numbers of kids who chose one of the other 2 schools ultimately for the commute.
Same for the likes of Putney, Wimbledon High etc. Everyone now always applies to both and again the same girls are likely to be offered a place. So even though the numbers are now huge I think (just my gut feel) is that the offers being made are also really high to compensate.