I think it’s a bit simplistic to say that the Whitgift Foundation just didn’t want to fund them in the way they are funding the others.
the £1billion shopping revamp property punt 12 years ago that blew up in their faces and burnt a big hole in their finances and the girls school closes?
The Foundation have owned the Whitgift school since 1600, they owned Old palace since 1993....guess which one closes?
Old Palace was always a local school in an unfashionable area, next to places like West Croydon Thornton Heath that many wealthy SW London parents would run a mile. Whitgift took a gamble they could get the daughters of the Whitgift crowd and they expanded the school massively with the leafy Melville Rd site, over the road from the Whitgift sports club, it didn't work which anyone could have told them wouldn't.
So you had the same crowd but a much bigger site , with some girls attending the Prep, their parents not dreaming of sending them to the main site (My friend was one who was aiming for Wallington or Croydon High at 11+, but was happy with the huge space her DD had at the Prep.
Pre- Whitgift , this would have never happened, as you chose the main site or didn't choose the school at all.
Old Palace's results were diluted after it merged with the non-selective Melville Rd school, (Whitgifts idea) which was the final nail in the coffin.