RICS Knowledgebase

This Valuation Office guide from 1982 covers a variety of asset classes and may be of use for your Capital Gains Tax (CGT) valuation 
https://webarchive.nationalarchives.gov.uk/ukgwa/20141002132829/http:/www.voa.gov.uk/dvs/propertyMarketReport/1982/index.html 

 Some commercial tools like CoStar also have some historical data 

The RICS library also contains a variety of sources including the Estates Gazette hardcopy issues from 1982. Contact knowledge@rics.org to get in touch with the library.