Please answer a question about the following article about Hunting:

Shooting as practised in Britain, as opposed to traditional hunting, requires little questing for game—around thirty-five million birds are released onto shooting estates every year, some having been factory farmed. Shoots can be elaborate affairs with guns placed in assigned positions and assistants to help load shotguns. When in position, "beaters" move through the areas of cover, swinging sticks or flags to drive the game out. Such events are often called "drives". The open season for grouse in the UK begins on 12 August, the so-called Glorious Twelfth. The definition of game in the United Kingdom is governed by the Game Act 1831.

When does open season for grouse begin in the UK?
12 August