Hi all,
I was holding off posting here until our windows were in but I can whole-heatedly recommend London Box Sash:
http://www.londonboxsash.com!
Our windows are in and they're just stunning. The whole process from Jack popping around with his sample window and talking us through everything to then meeting us at their local factory and showing us through their manufacturing process to installation was so ridiculously issue-free, that it's difficult to articulate.
London Box Sash come up a little more expensive that some of the others we spoke to (but definitely not the most expensive) but they're worth it.
The guys are all chilled out but professional. The windows were done a good month earlier than planned and they were all installed within a week, completely hassle-free and they look fabulous! It was also great to deal with a local, family-run business.
Given we're doing a full house refurb and are facing issues with pretty much every other aspect of everything we're doing, these guys were a breath of fresh air.
Anyway, if you're looking for great sash windows, check out these guys and feel free to drop me a line to come by and check out ours as a reference installation if you're near SW17.
SFK