Hi Lisa
I had great success with getting information from Calderstones Mental Hospital back in 2008.
My husband's aunt was placed there & she was rarely spoken about - my husband's youngest sister didn't even know about this aunt !
I originally had some trouble getting a return email but finally my email was sent to the right area. Try this email - & mark it as Medical records - archives (The email I had was an actual person's email - but they may not still work there so try this one...)
info@calderstones.nhs.ukWhen I sent my email to the right area - I explained that I wanted the information to obtain her medical condition & why she was originally admitted for family medical history reasons. We also asked about her death & place of burial. Attached to the email was a copy of her birth certificate that we already had & that had been issued in 1927 (she was born in 1926)
We received a reply very quickly giving a summary of the aunt's life. She was admitted to Calderstones in 1945 (19 years old) & discharged to a hostel in 1979 -where we have no idea what happened to her until her death in 1984. The summary from Calderstones filled us in on the institutions she had been in since the age of 5 ,some family history that we didn't know about & a general medical history. We didn't actually get any of her file but we were very happy with what we received as I had been searching & many other institutions destroy their records after 20 or 30 years (& it was free

).
Wishing you luck with your search !
Cathy