Personally I'd rather a bluish-purple stripe on First Class coaches if you ever were going to put anything on them. I think it's more pleasing to the eye than a yellow line running along the top, which I doubt will be any better than a "1" on the side of the window bands, simply because nobody is really going to be paying attention to the top of the train coaches. The fact most stations and boards now say where First Class can be found kind of makes it redundant in some areas. But then granted that's not the case at every station, so I'd rather opt for a line on the side beneath the window bands if anything. It just looks better if you ask me.