Whilst the front of a jacket is defined by the number of buttons it has, the back is defined by the number of vents. The front of the jacket has different kinds of lapels and pockets to break it up and give it interest whilst the back has only vents. The vents are a very important part of the jacket since they add functionality as well as distinguish the look of the back.
Single vents (also called centre vents) are when the centre back seam of the jacket is opened at the bottom. Single vents are most associated with American clothing, but like most origins in tailoring they come from England. Single vents were developed for riding, and the single vent splits the jacket’s skirt evenly on either side of the horse. Naturally, the hacking jacket, like what Sean Connery wears in Goldfinger and George Lazenby wears in On Her Majesty’s Secret Service, has a single vent, and it’s quite a long single vent (12 to 13 inches) so it has enough room to split neatly over the back of a horse. Many of Sean Connery’s and Daniel Craig’s suit jackets also have single vents, which is the most tradition vent style on a single-breasted jacket. Single vents have the disadvantage of exposing the buttocks in action scenes or when a man reaches his hands into his trouser pockets. It’s a bit less of a disadvantage with a body like Daniel Craig’s, though double vents would still look neater.
On suit jackets, the length of a single vents typically range from 8 to 10 inches.1960s fashions sometimes resulted in shorter vents around six inches long, though James Bond never succumbed to this fashion. Longer vents of around 12 to 13 inches were popular in the 1970s and early 1980s, though the only long single vents Bond wears at that time are on his safari-esque sports coats in The Man with the Golden Gun and The Spy Who Loved Me.
Double vents (also called side vents) are when the rear side seams are opened at the bottom, and they are typically associated with English tailoring. Double vents didn’t become standard for English tailors until the late 1960s. At that time it was more of a trend, but the trend stuck. Before the late 1960s, English tailors generally would put single vents on single-breasted jackets and double vents on double-breasted jackets. This system creates a symmetry between the front and back of the jacket. Double-breasted jackets should never have single vents, only double vents if it has vents. Double-breasted jackets take double vents on the back to balance the double columns of buttons in front.
For the past decade, double vents have been very popular and can be found on Italian clothing and American clothing. Currently, double vents are most popular on English, American and Italian tailoring. They haven’t been this popular in America since the 1960s and in Italy since the 1970s. Double vents are dressier than single vents, though they still have their origins in riding like single vents have. They allow more waist suppression than single vents do, and they allow a man to reach into his side trouser pockets with the least disruption to the lines of the jacket. They also extend the line of the leg for a slimmer and taller appearance. Like with single vents, double vents are typically 8 to 10 inches in length but varied with fashion trends. 6-inch double vents weren’t uncommon in the 1960s, and double vents up to 13 inches deep weren’t uncommon in the 1970s to the early 1980s. When over 10 inches, double vents can be a bit unruly, but that’s part of the charm.
Double vents sometimes continue the line of the side seams straight down, which can cause the vents to stick out over the rear. The double vents on Sean Connery’s Anthony Sinclair suits are made like this and emphasise his large rear. The double vents on Roger Moore’s Cyril Castle suits and Pierce Brosnan’s Brioni suits are also made like this, but their rears aren’t as large so the style work better on them.
George Lazenby’s Dimi Major suits, Roger Moore’s Angelo and Douglas Hayward suits and Daniel Craig’s Tom Ford suits in Quantum of Solace have double vents that flare outward. By flaring out, the vents actually hang straighter down the sides of the body. This keeps the vents looking neat no matter their length. Whilst the flare is noticeable from the back, the flare gives added shape to the waist whilst masking a large rear. The flared double vents have a more English look than straighter double vents have.
Jackets without any vent are most associated with Italian clothing, and the Italians did indeed make jackets without vents in the 1950s and later in the 1980s through the early 2000s when vents were commonly found on English and American tailoring. A non-vented skirt is not an Italian style, as often stated. It’s a traditional style for all tailoring, and before vents became popular in the 1950s most jackets were made without a vent. When the non-vented style was popular in the 1980s, many sports coats were made without vents, but sports coats usually have vents due to their sporting heritage. Sean Connery wears many suit jackets without vents in his Bond films, especially in Goldfinger and Thunderball. Timothy Dalton also wears jackets without vents in Licence to Kill, a result of the trends at the time for non-vented jackets.
All of the Bond actors, except George Lazenby, have at times worn dinner jackets without vents. Roger Moore’s double-breasted dinner jackets in The Spy Who Loved Me and Moonraker are his only jackets of the series without vents. Vents are still considered by many to be a faux pas on a dinner jacket, since vents have sporting origins and the dinner jacket is never worn for sports. When Bond has vents on his dinner jackets they are double vents. The exception to this is the single vent on his dinner jacket in Skyfall, though single vents are too sporty and not dressy enough for dinner jackets.
Some people recommend different style jacket skirts for different types of builds. I’ve heard people say that single vents are better for a large rear than double vents are. I’ve also heard people say the opposite. Others say that no vent is best for a large rear. Poor-fitting jacket skirts can cause any kind of vents to split open or stick out. Poor-fitting double vents can have a “shelf” effect where the back flap sticks out. A tight skirt or waist with a single vent will cause the vent to open, revealing the buttocks. A tight skirt without any vents will pull the front of the jacket open at the hips and cause creasing at the back. These are all ready-to-wear issues. When the skirt of a ready-to-wear jacket is too tight, it can be difficult to fix, though letting out the waist helps in some cases. A bespoke tailor can create a well-fitting and flattering jacket skirt for any build in any vent style.