About half the homes I've lived in (maybe a dozen?) were built before WW1. Lots of Victorian conversions.

My house is from the 1870s.

No? It would be pretty remarkable if the majority of all UK housing was built in a single decade. If you meant to say 'from before the 1970s' then that might be a more defensible claim. But old houses can be upgraded with double glazing, insulation, etc.