Bannermen

The Bannermen were a criminal group led by Gavrok. They waged a genocidal war against the Chimerons leading them into confrontation with the Doctor.

Tactics
The Bannermen used zap guns as their principal weapon, firing in the general direction of targets as opposed to aiming carefully. They rarely took prisoners without a specific reason and would not release them willingly. They used booby traps to kill their foes and seemed unconcerned about such underhanded tactics. They displayed no appreciation for Galactic Law. (TV: Delta and the Bannermen)

Weapons
The Bannermen's primary weapon was the zap gun. They used high-impulse beams to detonate devices such as radio transmitters.

Vehicles and devices
The Bannermen Warfleet was composed of large, three-engined cruisers. Their craft had scanners that could search for high technology. They had sonic cones to booby trap objects. (TV: Delta and the Bannermen)

History
The Navarino knew of Bannermen war fleets and were scared of running across them.

Exterminating the Chimerons
After polluting their own world, the Bannermen attacked Chumeria in an attempt to kill all Chimerons and take their world. They killed all the Chimerons except for Delta, the Chimeron Queen, who escaped. They followed her to toll port G715. Delta escaped from them by boarding a Nostalgia Tours bus.

On Earth
An informer alerted Gavrok that Delta was in Shangri-La camp in Wales, Earth, 1959. Gavrok killed the informer with a high-impulse beam to avoid paying him. They scanned the area to high technology and located the camp; they slaughtered an entire Navarino tour craft in the belief Delta would be on board and when that failed, they held Melanie Bush and Burton as "bait" for the Doctor and Delta.

The Doctor and Bannermen leader Gavrok faced off when the Doctor came under a flag of truce - which the Bannermen ignored. Gavrok was unconcerned at the threat of facing trial and justice, believing the Doctor could not defeat him. The Doctor was then allowed to leave with his friends, in order to lead the Bannermen to Delta's hideout. To prevent any escape, a sonic cone device was placed around the TARDIS.

However, the Doctor found and removed their tracking device and rigged the former hideout: honey fell on them and caused Goronwy's bees to attack them. The Bannermen reorganised and moved to attack the camp. However the amplified singing of the Chimeron princess sent them into disarray and Gavrok fell within the perimeter of the sonic cone and was atomised.

The remaining Bannermen were taken prisoner. Delta and Billy placed them on their craft when they set out for space. (TV: Delta and the Bannermen)

Other realities
In a parallel universe in which Britain was a fascist state known as the Republic of Great Britain, two of the Bannermen spacecraft were captured by the Republican Security Forces and mined for technology by the British government, allowing them to enhance two experimental space shuttles with gravity-control and a much faster drive. (PROSE: The Face of the Enemy)

Behind the scenes

 * It is unclear if the Bannermen were a race or just a paramilitary group.
 * In the novelisation, Gavrok earned his name "GavroK the Merciless" in "a few short aeons." Apart from being a description, this may indicate the Bannermen were a long-lived race.
 * Bannerman Road is the road where Sarah Jane Smith lived. This may be a reference.