Actually, the "clean window" thing was more of a metaphor, just meaning "clean" or "good " service in many ways---like "keeping your nose clean". It was that more than a literalism.
It is sort of like saying the EB was so good in every way that even such a detail as the windows being kept clean was not over-looked.
And, if I am not mistaken, the article was written by David Morgan, premier long term long time editor of TRAINS.