In another topic,
Channel Island predecimal SHORT sets, I have already mentioned the fact that, immediately before decimalisation in 1971, both Jersey and Guernsey had two low denomination local coins circulating alongside a full set of UK coinage:
1] Jersey: local coins were one twelfth of a shilling and one fourth of a shilling, equivalent to a predecimal UK penny and threepence.
2] Guernsey: local coins were a Guernsey threepence, and also 8 doubles, which was equivalent to a predecimal UK penny.
Immediately prior to decimalisation, the full UK set of coinage was 1d, 3d, 6d, one shilling, two shillings (florin), and a half crown (two shillings and sixpence).
Jamaica had a similar situation, prior to adopting the Jamaican dollar in 1969, when a Jamaican halfpenny and penny circulated alongside a full set of UK coinage.
British Guiana, prior to adopting the West Indian / British East Caribbean Territories dollar in 1955, had a similar situation, where a four pence coin circulated alongside a full set of UK coinage. A four pence coin no longer existed in the UK at that time, apart from the Maundy coin, which was only used by royalty for ceremonial occasions.
Was this a purely British phenomenon, or can anybody think of other situations in which a short set of local coins was supplemented by overseas coins of the SAME currency system?