The Thirsty Pine in Gloucester are holding a fight out between 16 cask brewers (15 Gloucestershire breweries plus Prescott (brewed in Devon by Hanlons)). Each is providing 1 cask and the first to run out in a battle between another brewery goes forward to the next round.
The challenge runs from April to July. (Click on image below to enlarge)
More details can be found in this article from Punchline Gloucester.