Hi
There is an article with photographs, about the Reformatory in a book entitled Ottaker's Local History Series Gloucestershire Compiled by Chris Fletcher. ISBN 0 7524 2281 2. It has a picture of the Superintendent standing in front of the building c. 1900. The article describes the setting up of the Reformatory and how the inmates spent their days. I don't know whether the book is still being published as it dates back to 2002 but it may be available on book selling websites.
The article was written as an entry for a competition run by Ottakar's book shop, when local people could write about various places and events in Gloucestershire. I have a copy of the book as an article I wrote appeared in it.