This is from a military married quarter prospective.
Anglian were ocntacted to replace hundreds of windows on camp. Now I am not sure if htey contract some of the work out, but the windows were crap and the workmanship was awful. Our neighbours had a big gap at the top of their front window!! Our windows didn’t shut and open properly. When it came to redoing the windows in my house, they were first on the list to avoid!