county

A person (or group of people) who unexpectedly shows up to, gives an opinion on, or contests something. It refers to the counting of ballots on election day, as votes are aggregated by county. Oh great, Mary's here to voice her opinion on the matter, yet another county heard from.

An unexpected person has spoken up or arrived on the scene, as in Jane's cousin from California decided to contest the will-another county heard from. This idiom originally alluded to the counting of returns on election night; it appears in that context in Clifford Odets's play, Awake and Sing (1931). However, it may echo the much older phrase, another Richmond in the field, alluding to Henry of Richmond (later Henry VII of England), chronicled in Shakespeare's Richard III (5:4): "I think there be six Richmonds in the field; five have I slain today." Whatever the origin, today it simply refers to an unforeseen participant or attender.