The Britons' main advantages are in their ranged units as they arguably have the best foot archers. Their arbalests and Archery ranges are cheaper and Its hero Richard the Lionhearthed have a power that gives +1 range to friendly archers in his line of sight. Their unique unit, the Longbowman, is the best foot archer in the game. The Britons also have discounts on Churches, Longswordsman, 2 handed swordsman & Champions which helps protect their archers against enemy units that get too close. However their cavalry and siege weapons are weaker as the Horse Archer, Camel, Onager and Bombard Cannon are more expensive.
They also have mining bonus.
The Britons appear several times in the single-player campaigns.
The language spoken by the Briton units is presumably a variant of Middle English, as it has some French and Latin words added that were not present in Old English. The monks speak Latin like the Byzantines.