Hi(posted 7589 days ago)Try HBOS web site - house retail price index -
http://www.hbosplc.com/view/housepriceindex/historicaldataspreadsheet .asp
This spreadsheet has house prices (and other interesting stuff) from early 80's
Remember though if you intend to sue or counterclaim regarding underselling a limitation period applies and therefore it needs to be within 6 years of your statutory notice (letter from lender telling you they have sold the house and for what amount).
Hope this helps