At the first pigeon and cage bird shows birds were exhibited in pairs, Pigeon Societies today still uphold this tradition in at least one or two classes. Two and three pair classes are held by the Peristeronic Society, which dates back to Darwin's time, in conjunction with the BPSS show which is held each December in Yorkshire. Other Societies that cater for these classes are Swansea Variety Pigeon club and Reading Fancy Pigeon club. The classes are for birds of the same breed and colour.