It really depends. I picked up their "Brutal London" book for just that purpose, and I'd say about 75%-80% of the buildings are spot on in scale (give or take a tiny margin). The rest (models of high-rise skyscrapers or the National Theater) are going to be noticeably out of scale, but the majority (models of what they call "Council Estates") do work fairly well for BattleTech terrain purposes.
