Elite unit that carries huge responsibility

The 400 officers in the Met's elite firearms unit, also known as SO19, carry a massive responsibility.

Most spend their days in armed response vehicles, known as ARVs, ready to speed to any dangerous incident when called for by colleagues.

Others serve as back-up to units such as the Flying Squad on pre-planned missions where intelligence suggests that suspects will be armed.

SO19 officers wear body armour and carry Glock 17 selfloading handguns by their sides. ARVs carry Heckler & Koch MP5 machine pistols.

Up to to 13 cars and 100 SO19 officers are available to protect London at any time.

While about 2,000 Met officers are qualified to carry firearms, and some regular officers are called upon to do so as the need arises, it is only SO19 that provides regular armed back-up to police on routine duties.

Last year SO19 officers were called out to 13,936 incidents. Most were resolved before they arrived and they only got out of their cars on 2,327 occasions.

Since 1997, Met officers have fired weapons on only 20 occasions. Almost all the incidents involved officers from SO19. Their guidance is to shoot only if their own safety or the safety of the public is at risk.