Historical House Prices / Querying Council Tax Band

Hi, I'm currently disputing my council tax band and despite what I believe to be clear evidence, it's proving to be quite difficult.  My final option is to look up the sold prices for about 50 houses in my immediate area (all of which are built to the same spec, yet have differing bands) and hope that some of them were sold around 1991 - can anyone advise what form I need to use, what I need to ask for on said form, and the cost of each request (is there a bulk discount)?  Or are official printed records kept in local government offices that I can look through in person? Thanks in advance.

Hi Nicki - we only have online data re house prices back to 1985 so anything sold prior to that would not be available through that service - HM Land Registry: Price Paid Data - GOV.UK 
You can search online for a fee each address and check the respective registers piecemeal. And/or apply by post for a copy of any old Transfers depending on when the property was registered
I'm not aware that the local council would have any such records re sales/purchases and the amount paid but I would be surprised if it were information they would generally hold
I would recommend searching online re forums such as Money Saving Expert where such matters are often discussed and where the experiences of others might help