A very brief historical introduction
The Claudian invasion of 43AD signalled the beginning of the end of Celtic coinage in Britain. Britainnia became a province of the vast Roman Empire and during the first few centuries no local coinage was officially produced. Regular Imperial coinage from Rome was circulated.
Although Britain was on the outskirts of the Roman Empire a surprisingly large number of coin types alluded to events in the province, such as wars. Two mints were established in Britain - London and Colchester. London produced an enormous amount of base coinage until its closure by Constantine the Great, in 325AD. Other coins (copies) were produced unoffically in troubled times of the early 270's.
The withdrawing of the legions in 411AD by Honorius signalled the end of Roman Britain, although the civil administration continued until the the Teutonic invasions.