Honestly in our 3 months of searching and 3 months of waiting to complete, I've found so many incorrect listings for houses. Wrong dimensions that don't add up (I mean wildly wrong like thing two walls side by side are 9ft and 19ft)... Floorspace calculated wrong, all sorts. I appreciate those are outliers but don't come to rely on any one metric if an estate agent is the one entering it.
Our floorplan from the house listing we bought, shows the landings and bathroom/bedroom (same room location in different floors) as totally.differents sizes, shapes and layouts. Measure the house and they're literally identical per floor.