While it is unclear what species the Bannermen were, if they were actually a race called "Bannermen" or not, they were humanoids with increased strength, able to smash equipment, and had purplish blood; Arrex, however, commented that a car was a primitive mode of transport only fit "for a humanoid," implying Bannermen were something else. Gavrok was known to have earned his reputation in "a few short aeons," though whether that was through time travel or long lifespans was uncertain. (PROSE: Delta and the Bannermen)
The Bannermen were so-called because many of their shock troops wore red and black triangular banners, the insignia of their empire, along with their black, uniform jumpsuits, helmets or hats, and red-slit glasses. Gavrok believed that showing mercy was a sign of weakness, (PROSE: Delta and the Bannermen) and when cheering in victory, Bannermen would stick their tongues out and hiss. (TV: Delta and the Bannermen)
The Bannermen's primary weapons were guns with various settings, including small projectiles akin to bullets, flares, and violently explosive projectiles. They used high-impulse beams to detonate devices such as radio transmitters, ionising the victim. They also made use of booby traps like sonic cones.
The Bannermen existed outside of the Mutter's Spiral some time after 1959. After polluting the rivers and atmosphere of their own world, (PROSE: Delta and the Bannermen) the Bannermen attacked Chumeria in an attempt to take it from the Chimerons who were unaccustomed to war. They killed everyone except for Delta, the last Chimeron Queen, who escaped with an egg. They followed her to toll port G715, where she evaded them by boarding a Nostalgia Tours bus headed for Disneyland, Earth, 1959. Gavrok put a price of one million units for information about the Queen.
A bounty hunter on the bus contacted Gavrok when it crash-landed in the Shangri-La camp in Wales, only to be killed with a high-impulse beam after the Bannermen locked onto his signal. They scanned the area for high technology and located the camp, slaughtering the entire Navarino tour craft in the belief Delta was on board. When that failed, they held Melanie Bush and camp director Burton as "bait" for the Seventh Doctor and Delta.
The Doctor and Gavrok faced off after the latter ignored a white flag of truce, unconcerned at the threat of facing trial and justice, believing the Doctor could not defeat him. He was then allowed to leave with his friends, in order to lead the Bannermen to Delta's hideout, with a sonic cone device placed around the TARDIS to atomise the Doctor should he attempt to escape.
However, the Doctor found and removed their tracking device and rigged the former hideout: setting a trap, the Bannermen fell into honey and attracted Goronwy's bees to attack them. The Bannermen re-organised and moved to attack the camp, but by this point the maturing Chimeron princess used her attack singing to send them into disarray, causing Gavrok to fall within the perimeter of the sonic cone.
The remaining Bannermen were taken prisoner aboard their own ship, commandeered by Delta, the Princess, and Billy who would help to rebuild the Chimeron race after reaching the brood planet. (TV: Delta and the Bannermen) After dropping Delta and the Princess off, Billy took the Bannermen to the galactic prison star to await trial, while the Bannermen had already decided, since they were leaderless without Gavrok, that if they did get a chance to redeem themselves they would start a looming circle and weave blankets. (PROSE: Delta and the Bannermen)
Other realities Edit
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)