Glorious Twelfth is the twelfth day of August , the start of the shooting season for red grouse ( '' Lagopus lagopus scotica '' ) , and to a lesser extent the ptarmigan ( '' Lagopus muta '' ) in Great Britain and Northern Ireland . This is one of the busiest days in the shooting season , with large amounts of game being shot . The date itself is traditional ; the current legislation enshrining it in England and Wales is the Game Act 1831 ( and in Northern Ireland , the Wildlife ( Northern Ireland ) Order 1985 ) . Not all game ( as defined by the 1831 act ) have the same start to their open seasons – most begin on 1 September , with 1 October for woodcock and pheasant . Since English law prohibits game bird shooting on a Sunday , the start date is postponed to 13 August on years when the 12th falls on a Sunday . Because grouse are not and never have been reared to any extent for shooting , their numbers fluctuate naturally from year to year . In recent years , the Glorious Twelfth has also been hit by hunt saboteurs , the 2001 foot and mouth crisis ( which further postponed the date in affected areas ) and the effect of sheep tick , heather beetle , the gut parasite '' Trichostrongylus tenuis '' and severe flooding and bad weather . In some seasons where certain moors are hit by low numbers of grouse , shooting may not occur at all or be over by September
severe flooding and bad weather
2007 United Kingdom floods
Glorious Twelfth