Rowly
There are no general rules for the width of the trouser bottom but many tailors do start at 18 inches and move from there depending on the client’s physique or wishes.
As regards the quote from A&S, I think the style standard has always been for tapered trousers. In this regards it is not a trend. Just because a man has his clothes made by a tailor does not mean he has a notion of style. Many men have baggy pantaloons made for them while others choose skin tight silos of cloth that preclude walking in them. Tailored clothes are no guarantee of style, you are the guarantor.
The question is not as much “how much” taper as it is “what kind of taper?” If you start your investigation at the bottom of the trouser or the knee you’ve got things turned around. The taper starts and is determined by what goes on at the waist and hips.
Now a lot of younger guys want flat fronted trousers with a slimmer cut.
If a trouser is very trim at the top end how can it taper? If you look closely you will find that very narrow tops on trousers lead to a look of greater width at the bottom because there is a limit as too how small a bottom can be made and still be wearable. So a narrow top trouser winds up looking more like a silo and less like a cone, a look with little style.
Anthony Sinclair cut very slim clothes for Sean Connery in the 60s. This is about as slim a trouser can get while maintaining an elegant taper or what we call “line.”
Try to imagine Sinclair’s trouser with a jeans-like adherence at the waist and hips and you will see the bottoms of the trouser suddenly appear bigger.
Pleats are helpful to the extent that they give us width up top from which to taper and comfort without appearing too wide. For a non pleated trouser to provide the same width and comfort it would have to be too wide and too much width is inelegant. (Many Italian tailors I know refuse to even make non pleated trousers for this reason.)
A few members have asked me if the trousers in the following photo have pleats. They do. The trouser is in fact quite slim as slim as the Sinclair model. It tapers to a bottom of 17 inches from an ample measure at the hips.
Remember that your hips are covered by your jacket or coat. If you think the amount of width necessary to generate an elegant line is outdated and not sufficiently skin tight, you will be reassured to know that in practical terms, no one sees your hips. (Sports trousers meant for wear in summer without a coat can be made more jeans-like but they will never have the allure of a well tapered trouser.)
Cheers
M Alden
)