It's absolute rubbish. Most heating systems installed in the last 20 years or so have required them due to assorted building/env regs, and they were quite common place before that. Some low quality housing stock with old systems won't have them, but if the owners were to want one they would likely splash out the twenty quid for a standard one, or take advantage of the substantial grants available to those on low incomes for new heating systems.
I really hope for their sake Nest haven't bet the (UK) house on this "fact".
I really hope for their sake Nest haven't bet the (UK) house on this "fact".