Both are right, give or take a few quid
100sqm @ £150000 = £1500/sqm
1000sqft @ £150000 = £150/sqft
If you like to be exact, 100sqm is 1,076sqft. I like to keep things simple though! I actually don't know the exact cost of the house. As the build progressed I stopped counting exactly but gut feel is £150,000 for 100sqm inc VAT (some of which can be reclaimed) and professional fees but excluding land.