One of the principal characteristics of morning dress that make it so interesting and, I blush to say, exciting, is that it is not a uniform. With evening dress, particularly black tie, there may be plenty of room for flexibility in the small details provided that it is all done within THE RULES, but this doesn’t come close to the vast array of options available for morning dress. The most obvious points of variation are neckwear and waistcoats, about which I could go on for pages – I won’t even rattle on now about the cynicism of hire companies when it comes to these garments. Shirt, shoes, hat and coat can all vary in styles too, but one of the most unique aspects of morning dress is often taken for granted: The trousers, and specifically the fabric from which they are cut (like pretty much everything else I have mentioned so far, shape and cut will have to wait for its own outpouring of opinion and sentiment at a later time.)
In the majority of retail and hire settings, there is only one option: an elaborate pinstripe of black and shades of grey known as a cashmere stripe.
A typical formal cashmere stripe.
The actual pattern can vary quite significantly when inspected closely, but the effect to most onlookers remains much the same. Some sources seem to refer to any appropriate design of cloth as cashmere trousering, but for the sake of clarity I reserve it for these kind of stripes. It’s nice, it’s classic, but it is by no means the only option. Other perfectly acceptable alternatives are a black or oxford grey and white chalkstripe, and a black and grey houndstooth check.
An excruciatingly elegant man in subtle chalkstripe trousers
The choice is even greater than that, however. You may raise an eyebrow or two by wearing them, but shepherds checks, grey herringbones (or cheviots), and various other checks on a black and grey theme could also be considered by the daring. There are even precedents for plain grey flannel or twill if you want to play it a bit less formal. Hopefully these images will give you something to bear in mind before you decide to make your mark with a novelty patterned silk waistcoat.
A array of incredible legwear. From left to right: Bold, wide stripe; Houndstooth; Chalkstripe; Cheviot; Grey twill or flannel; Chalkstripe.
Two final thoughts on the above image. Firstly, it should be noted that a couple of these distinguished gentleman are actually wearing lounge coats and not morning coats. That’s another thing I’d like to talk about at some stage, but it’s hard to concentrate on the cut of a man’s coat when he’s impossibly tall. Indeed, it’s difficult to tell whether the artist of this image has absolutely no sense of perspective, or is a master of non-euclidean geometry.
Andrews
Andrews & Pygott: The Morning Dress Guide 
To say the least, menswear illustrations from bygone eras are VERY stylised. All men had impossibly long legs and wide shoulders in the 1930s-1940s. In the 1910s-1920s the illustrated male ideal was quite the opposite — diminutive and very slender, with sloping shoulders.
Oh, I fully appreciate what you’re saying, what I was principally driving at was the difference in height of the man at the back of the group and the man immediately to the right of the bride.
The men wearing “lounge coats” are actually wearing strollers.
As I suspect you already know.
Whenever I see this picture, I think of the impossibly tall man with the red carnation as “Lurch.”
Incidentally, drawings like this are based on what men were actually wearing at the time, rather than today’s fashion shots, which are based on a designer’s conceptualization.