Not sure if this deserves a separate thread but the issue of no opening windows on the air con CDL stock was closely linked to this topic at one point. On today's WCRC stock move from Burton to Carnforth - it seems one of the carriages in tow (seventh carriage in the consist) is out having been fitted with opening hopper windows:
(Link directs to video of WCRC stock move passing Lancaster with Blue MK2 rake, one of which looks to have opening windows)
Hopefully not long until this and other examples make it onto tours