Hello Clive,
I came across your posts whilst searching for information on Park House as I only found out recently that my mother gave birth to a daughter at this home in December 1945. I am using an after adoption support worker to help me try to find my half sibling but so far we have not had any success. In the meantime, I am continuing with my own efforts. Did you find out any further facts about the adoption records for the home? My mother's are not with the Hull authorities so York has now been contacted as it was part of the York diocese.
Regards
Pat