One true hallmark of a bespoke suit is the size of its armholes. Most armholes in ready-to-wear suits (and made-to-measure patterns, to a certain extent) cater for men with larger arms and shoulders, in order to be on the safe side. As with so many other areas of menswear, no one notices when they’re too big, but everyone would notice if they were too small. Smaller armholes are also just harder to make.
As bespoke is cut uniquely for you, the armholes can be as small as you want. And the biggest advantage of small armholes is that the arms can move independently of the body of the jacket, without dragging its chest and back all over the place.
Lift up your arms and see how far the waist button rises (when the jacket is done-up). With a bespoke suit, that movement is vastly reduced. So your collar stays on the back of your neck, your upper body is more consistently shaped by the jacket’s cut, and if you’re Fred Astaire you can dance and wave your arms around while still looking good. (Modern equivalent: it’s much easier to work at a computer for long periods, arms stretched forward.)
This effect is accentuated when a larger sleevehead is eased by hand into that small armhole, as accentuated by tailors such as Anderson & Sheppard and ready-to-wear by brands such as Kiton.
It would be great if a ready-to-wear suit could be altered to have smaller armholes. Unfortunately, it’s not that easy. A smaller armhole means extra material under the sleeve and in the body of the jacket – and most suits don’t supply any extra here.
There is, however, a cheat. If you get your tailor to insert a thin extra shoulder pad into each side of the jacket, it lifts up the armholes and effectively makes them smaller – as the pad at the top is taking up some of that armhole space.
The downside is that you have bigger shoulders. But I don’t mind this. As I have sloping shoulders anyway, I tend to ask tailors to build in a slightly heavier shoulder pad. And increasing the padding in a ready-to-wear suit also lifts up the drape of the jacket, removing the folds that collect next to my sleeves in the back (due to those sloping shoulders). So it suits me both ways.
The effect is not the same as a genuinely smaller armhole, of course. The circumference is still the same. But it gets partway there and is certainly an improvement. I wouldn’t recommend it for men with large or square shoulders, and the insert should always be pretty slim, but if you happen to have a similar body type to me, I recommend trying it.