At most evening mess functions your host will wear Mess Dress the civilian equivalent to this is either white tie or black tie, for the vast majority of cases it will be black tie. Below is a guide on the equivalent standard of dress.
Ladies Evening Wear
For Ladies 'ladies equivalent dress' can be complicated as it varies from event to event. It is important to ascertain from your host the level of formality of the occasion and the service and ship or regiment hosting the event. Generally dress and formality of events can be broken down two main categories: more formal occasions such as dinners, and less formal events such as balls and parties. Thus it is important to ascertain from the host what dress he/she is expecting.
The choice of long or short dress can also be vexing. Traditionally long is more formal than short, but these distinctions are fast disappearing . . . The choice today is largely based on what suits the wearer, her legs and her relative age. Long is the preferred comfortable option of older women, while young girls invariably feel more suited to short. However, a long dress or skirt remains the safest option for all, as it is always special, and appropriate to any black tie event grander than a cocktail party. Best jewels, with plenty of sparklers, can be worn, but obviously tiaras are inappropriate.
As a general rule dresses should be no shorter than just above the knee and whilst dining the shoulders should be covered.
As society’s most formal dress code, White Tie maintains relatively strict requirements for feminine attire. In the United States, Emily Post's Etiquette says simply that women should wear a “formal evening gown” while Letitia Baldrige's New Manners for New Times recommends “a full-skirted ballgown, lots of jewelry but never too much, fur wrap, long white gloves.”
Mens Evening Wear
For men, the elements of black tie are a suit, of black or midnight blue wool, in which the jacket lapels and trouser braid are of silk or other contrasting material, a white dress shirt, a black bow-tie, an evening waistcoat or cummerbund, and black dress shoes. An example of which can be found on Amazon.
The elements of black tie
Unlike white tie, a man has sartorial options in choosing his dinner jacket and accessories.
The elements of a traditional black-tie ensemble are:
• Short or medium black jacket which may have grosgrain- or satin-faced lapels
• Black trousers with or without silk braids matching the lapels
• A black cummerbund or a low-cut waistcoat
• A white dress shirt with either a marcella or a pleated front
• A black silk bow tie
• Black dress socks, often made of silk
• Black patent leather shoes or highly polished black leather shoes
The typical black-tie jacket is single-breasted, ventless, constructed of black or midnight blue wool, which may be faced with either grosgrain (ribbed silk) or satin. The most traditional lapel type is the peaked lapel, derived from its tailcoat predecessor; the shawl collar (with rounded lapels) is used also. Currently, both styles can be either single- or double-breasted. The traditional single-breasted jacket has a single-button closure, with two-button variants sometimes seen; jackets incorporating more buttons are fashion fads. (Also see: smoking jacket)
The colour black may have a green hue in artificial light, if aesthetically unacceptable to the man, midnight blue (introduced by the Prince of Wales) is the acceptable alternative colour;other colours are fads.
Black-tie suit trousers have no turn-ups (cuffs) or belt loops. The outer leg seams may be decorated with a single, silk braid matching the lapel facing.
Waistcoat and Cummerbund
The waist is dressed in either a waistcoat (vest) or a cummerbund (not both) when wearing a single-breasted coat. Usually, the waistcoat is low-cut, has a three-button stance, and of the same cloth as the jacket. The cummerbund sash (from military dress uniform in British India) is worn pleats up, and is of the same cloth as the bow tie and lapels.
The Shirt is conventionally white or off-white (cotton, linen, silk) and its front either is cotton marcella (as in white tie) or pleated.
A shirt with a fold-down collar is the U.K. norm. (winged collars are the US norm) The original, and most formal, version of the dress shirt usually fastens with matching shirt studs and cuff links. In lieu of studs, a buttoned shirt with either a fly-front placket or a French front (sans placket) is worn.
The Bow Tie is typically made of silk barathea or satin and is knotted by hand. It is considered poor form and déclassé by some to wear a commercially pre-knotted clip-on or hook fastened bow tie.
Traditionally, the most formal shoes are patent-leather opera pumps (court shoes) decorated with a ribbed silk bow, as worn with white tie; they are uncommon today. A popular, formal
alternative is the black leather lace-up Oxford shoe, often in patent leather, but without a toe cap or decorative brogueing. Too-informal for black tie are shoes with open lacing, i.e. "Derbies".