I am Lynda who started this thread. I would be interested if you find out any information about Park House files. I have contacted many Government and support agencies in various parts of Yorkshire but no one had the files. This was a York Diocesan maternity home so perhaps the Church of England might have the files. Years ago I contacted Bradford diocese but had no reply. The actual building on Pot Lane in Steeton is still standing and has been converted to flats. There is a picture of it on the Steeton website. I did request and receive a copy of my baptismal registration from Bradford archives, which hold the archives for St. Stephen's Anglican Church, Steeton. I live in Vancouver, Canada so my searching has to be by post or email.
Good luck, Lynda