[DaiPlusPlus]

Double-glazing is popular in the UK - but it was a late-adoption: I didn't see it become popular until the early-1990s (I note this would be shortly after the privatization of British Gas, hmmm!)

A contributing factor is the popularity of rented accommodation, including council-owned houses, where the pressure to invest in double-glazing is less (as tenants are responsible for gas/elec bills, but landlords are responsible for capital-expenditures and improvements) - so there's not much incentive to upgrade windows in that case.

But all new houses I've seen built since the late-80s all tend to have double-gazed windows, the majority have white PVC framing, but I see wooden ones occasionally too. I've never seen white PVC window framing turn yellow - my parents had their windows converted around 1994 - now 23 years later the frames are still pristine white - and I'm not aware of any special treatment or care they require.

That said, public perception of double-glazing salesmen isn't the best - they were the butt of many a joke in the 80s and 90s, including Blur's Parklife video: https://www.youtube.com/watch?v=YSuHrTfcikU - though I never understood myself, perhaps because they were a commonplace sighting?

That... and even today they seem to capitalize on their public perception with intentionally gauche TV ads: https://www.youtube.com/watch?v=OgqJPd_YJtE

[anothercomment]

Thanks for the clarification!