Hi Hertford
How long ago was your g aunt's research done? A friend told me that they had changed the 100 year rule so she was able to view her relatives records. I'm sorry I can't remember what they'd changed it to. I just checked and the record office research fees are now £23 per hour.
Last year, we viewed and photographed the pages pertaining to my husband's g uncle who was in the institution from 1900-1923 when he died.
The records were extensive and very informative, naming his father and giving details of his illness. We even have a photograph of him, so we were fortunate.
Incidentally, the hosptial was called The Berrywood Aslyum (Upton) in early times.