Brown sauce (or "broon") is a traditional British condiment made from malt vinegar and fruits that commonly accompanies a bacon sandwich, chip butty or Jeely piece sandwich, as well as the traditional Full English Breakfast. The exact recipe for this sauce varies from maker to maker but all are a closely guarded secret, similar to the Coca Cola recipe.
Popular brands of this sauce include HP, Daddies and Chop. HP Sauce is perhaps the best known and best loved variety but Chop and Daddies sauce are the sauce of choice in British Chip shops. Although originally sold in glass bottles, more recently squeezy plastic bottles have been introduced as being more consumer friendly and minimising the need to shake the inverted bottle.
The original brown sauce is HP sauce which features a picture of the British seat of government.