The Fosters left the House in 1936 and it was given to Bradford Council to be managed as a Charitable Trust.
The Charities Comission can be seen here
Extract from the Central Register of Charities:
Deed of gift dated 17th September 1936
Objects – For the purposes of a public park and recreation ground for the benefit and use of the inhabitants of Queensbury and the public and to be associated with the silver jubilee of his late Majesty King George the fifth and in the memory of the said Herbert Anderton Foster.