Every racing country runs elite races for their very best horses. In the 1970s, the major European racing nations cooperated to produce a template to specify when and where those elite races should be staged in Europe.
The idea was to avoid similar races clashing in the calendar, resulting in a dilution in quality and field size for each, and to certify the continuing quality of those races. This framework became known as the Pattern and has been copied throughout the world.
The highest level of contest is known as Group 1 or Grade 1; Group 2 and Group 3 races are the next two levels below in this hierarchy.
The continuing status of these races depends on handicappers from around the globe agreeing on their yearly performance figures. The average figure for the first four horses in each year’s renewal is then in turn averaged with those from the previous two years. That three-year average must fall within certain parameters in order for the race to retain its status. In rare cases, there can be exceptions to this strict process of upgrades and downgrades.
The International Federation of Horseracing Authorities agrees on the standing of each race based on those figures and taking into account the history of the race.
British Group 1s include races like the Derby, the Gold Cup at Royal Ascot or the Nunthorpe Stakes on the Flat. Over Jumps, races like the Champion Hurdle and Cheltenham Gold Cup are included.
In 2018 Britain staged 36 Group 1 races on the Flat, 40 Group 2 races and 73 Group 3 races. Over Jumps in Britain, there are 40 Grade 1, 67 Grade 2 and 40 Grade 3 races. The premise of Group races is that they should be level-weights contests to determine which horse is best, but the conditions always incorporate allowances for fillies/mares competing against colts/geldings and the weight-for-age scale. Horses that have recently won at that grade or higher are usually also required to carry a penalty.
Listed races are the stepping-stone between handicap races and the Pattern, with the weights carried determined in a similar way to Group races.