The building you were in was the admin block, patients only went there to eat or to the ball room. The "slabs" down in the cellars there were actually cold stores which were used to prepare food. There was a farm on the estate and animals were used for food , so the area does look like a mortuary but it wasn't. In the same building, there was accommodation for the matron and chief medical officer. Also a bank, library , dispensary, shop, hairdressers , and reception and board rooms , the main one having the ornate stone fireplace. There were also lots of admin offices and records storage . The kitchen , stores and dining room were at the rear of this building. The railway used to access the stores area at one time , bringing in coal and supplies. As said , the mortuary is long gone and the equipment , I believe is in a museum in Leeds .