Not necessarily new places, they're just trying to lure those who'd otherwise go to Highgate, SHHS, USC etc. We applied both to Alleyns and Hampstead schools so they know their customer base. Some families are not very keen on single sex schools, and only Highgate is co-ed in that area (NBH is not in the same league).
I'd say it's more a sign of increasing competition between schools rather than expanding the number of places.
Our former school used to attract 10+ applications per place, they very rarely had occasional places, only when families moved abroad, and those places were filled in quickly. Now they have a few places in most year groups. They are still academically selective and I don't know what they are going to do. They can't accept whoever comes as that would damage academic league tables and will in turn lead to falling number of applications.