The Metropolitan Police officers were unarmed to clearly distinguish them from military enforcers, which had been the system of policing seen before the 1820s. Their uniform was also styled in blue, rather than the military red. Despite the service being unarmed, the then Home Secretary, Robert Peel, gave authorisation to the Commissioner to purchase fifty flintlock pistols, for exceptional incidents that required the use of firearms. As time progressed, the obsolete flintlocks were decommissioned from service, being superseded by early revolvers. At the time, burglary (or "house breaking" as it was then called) was a common problem for police, as house breakers were usually armed. Due to the deaths of officers at the hands of armed criminals in the outer districts of the Metropolis, and after much press coverage debating whether Peel's service should be fully armed, the Commissioner applied to the Home Secretary to supply all officers on the outer districts with revolvers. These could only be issued if, in the opinion of the senior officer, the officer could be trusted to use it safely, and with discretion. From that point, officers who felt the need to be armed, could be so. The practice lasted until 1936, although the vast majority of the system was phased out by the end of the 19th century.
From 1829, to 1839, Metropolitan Police officers wore blue swallow tail coats with high collars to counter garroting. This was worn with white trousers in summer, and a cane-reinforced top hat, which could be used as a step to climb or see over walls. The sleeves of the dark blue coats originally had a pattern of white bars, roughly 6 mm wide by 50 mm high, set roughly 6 mm apart. This immediately distinguished them from naval or maritime personnel. In the early years of the Metropolitan Police, equipment was little more than a rattle to call for assistance, and a wooden truncheon. As the years progressed, the rattle was replaced with the whistle, swords were removed from service, and flintlock pistols were removed in favour of revolvers.
In 1863, the Metropolitan Police replaced the tailcoat with a tunic, still high-collared, and the top hat with the custodian helmet, which is based on the Pickelhaube. With a few exceptions (including the City of London Police, West Mercia Police, Hampshire Constabulary and States of Guernsey Police Service), most forces helmet plates carry a Brunswick star. The helmet itself was of cork faced with fabric. The design varied slightly between forces. Some used the style by the Metropolitan Police, topped with a boss, while others had a helmet that incorporated a ridge or crest terminating above the badge, or a short spike, sometimes topped with a ball.
The tunic went through many lengths and styles, with the Metropolitan Police adopting the open-neck style in 1948 (although senior and female officers adopted it before that time). Senior officers used to wear peaked pillbox-style caps until the adoption of the wider peaked cap worn today. The custodian helmet was phased out in Scotland in the early 1950s.
Female officers' uniforms have gone through a great variety of styles, as they have tended to reflect the women's fashions of the time. Tunic style, skirt length and headgear have varied by period and force. By the late 1980s, the female working uniform was virtually identical to male, except for headgear and sometimes neckwear.
Formal uniform comprises an open-necked tunic (with or without an attached belt, depending on the force and rank of the Officer) and trousers or skirt, worn with a white or light blue shirt and black tie (usually clip-on, so it cannot be used to strangle the wearer). Although most forces once wore blue shirts, these have been less used since the 1980s, and most now wear white. Officers of the rank of Inspector and above have always worn white shirts, and in many forces so have female officers. In some forces, female officers wear a black and white checked cravat instead of a tie. Officers of the rank of Sergeant and above wear rank badges on the epaulettes of their shirts, while Constables and Sergeants also wear "collar numbers" on them. Shoulder numbers in the Metropolitan Police are displayed on the shoulder of the tunic (despite the lack of epaulettes on the tunic in junior ranks) as are all rank insignia (except for that of Sergeant, which are displayed in the form of a sewn-on badge on the sleeve). No.1 dress is worn with black, polished shoes or boots. Male Constables and Sergeants in English and Welsh forces wear the Custodian Helmet with this dress, whereas the peaked cap is worn by Inspectors and above. In Scotland, all male officers now wear a peaked cap. Female officers of all forces now wear bowler hats. At more formal occasions, such as funerals and parades, white gloves are worn.
Until 1994 the No.1 Dress was also the everyday working uniform, but today it is rarely seen except on formal occasions. The normal working dress retains the shirt and trousers. In some forces short sleeved shirts may be worn open-necked. Long sleeved shirts must always be worn with a tie or cravat, worn with or without a jersey or fleece. If a jersey, fleece or jacket is worn over a short sleeved shirt, then a tie must be worn. In 2003, Strathclyde Police replaced the white shirts with black wicking T-shirts with stab vest on top, for the majority of officers on duty. Some forces use combat trousers (trousers are of a cargo pocket style i.e. two thigh pockets and two conventional side and rear pockets) and boots. Today, female officers almost never wear a skirt in working dress, and sometimes wear trousers in formal dress as well. Officers also frequently wear reflective waterproof jackets, which have replaced the old greatcoats and cloaks traditionally worn in inclement weather. Most officers now wear stab vests, a type of body armour, when on duty.
Basic headgear is a peaked cap for men, and a round bowler style hat for women. All officers wear a black and white (red and white for the City of London Police) diced band (called Sillitoe Tartan) around the hat, a distinction first used in Scotland and later adopted by all forces in Great Britain. Traffic officers wear white cap covers. On foot duty, male constables and sergeants outside Scotland wear the familiar conical custodian helmet. There are several patterns, with different forces wearing different types. Although some Scottish forces have used helmets in the past, they are no longer worn in Scotland. The only English police force to have abandoned the custodian helmet is the Thames Valley Police.
The Metropolitan Police approved the use of name badges in October 2003, and new recruits started wearing the Velcro badges in September 2004. The badges consist of the wearer's rank, followed by their surname. Senior officers wear these in No.1 Dress, due to the public nature of their role.
Increasingly officers are wearing 'Tactical' uniform to perform everyday roles as the increased level of equipment carried on the police duty belts and operational requirements expand.
Officers of the Police Service of Northern Ireland (PSNI) wear a uniform which is somewhat different, reflecting the different roots of the force and nature of the role that it carried out for much of its history. The main colour to be found is a dark and light green with the uniform looking very unlike police uniforms over in Great Britain. The RUC officially described this as 'rifle green', that is to say the same colour as used by Irish and rifle regiments of the British Army, such as the Rifles (formerly the Light Infantry and the Royal Green Jackets) and Royal Irish Regiment. This reflects the force's de facto status as more of a paramilitary force, or gendarmerie, than police forces in Great Britain. When the six new versions of the PSNI uniform were introduced, in March 2002, the term 'bottle green' was used for basically the same colour. This was perhaps seen as being a less confrontational description and having less of a military connotation, in keeping with the spirit of the time. RIC uniforms were originally a very dark green almost black colour. The custodian helmet was never worn by either the RUC or the PSNI, although a similar design known as the "night helmet" was worn on night shifts by the RUC until the early 1970s, and previously by the RIC.
The mounted police of the Greater Manchester Police and of the Merseyside Police wear a ceremonial uniform which includes a distinctive cavalry-style helmet, similar to those worn by the Household Cavalry. Mounted police in Cleveland wear a similar uniform, but with a red rather than a white plume.
Police Officers may wear mess dress to formal dinners if appropriate but is most usually worn by officers who have achieved the rank of Superintendent or above. The mess dress of the Commissioner of the Metropolitan Police is dark blue with light blue facings on the lapels and includes a two-inch oak leaf lace strip on his trousers and a set of aiguillettes.
The Commissioners and other senior-ranked officers of the Metropolitan Police Service and the City of London Police wear a full dress ceremonial uniform on State and special occasions (see External links below); this includes a high-necked tunic with silver or gold trimmings and is worn with a sword and a plumed hat.