the territorial support group (tsg) is a met operations unit of london's metropolitan police service (mps). in 2012 it consisted of 793 officers and 29 support staff. it specialises in public order containment, among other specialist policing. the tsg is a uniformed unit of the mps that replaced the similarly controversial special patrol group in 1987. tsg units patrol the streets of london in marked police vans or "carriers"; using the call sign "uniform". generally each carrier has an advanced (police) driver, five constables and a sergeant. territorial support groups often comprise three carriers, eighteen constables, and three sergeants reporting to an inspector. they separately patrol designated patches. when deployed, it is by the mps information room. due to the public order nature of their role often numerous carriers will be assigned, a common situation being drunken rowdiness at public house closing time. tsg officers can be identified as tsg from the distinctive "u" in their shoulder numbers.