Vice counties are a special category of boundaries which are used for biological recording in the United Kingdom and Ireland. Initially invented by Watson for Great Britain in the 19th century, the concept was extended to Ireland by Praeger in the early twentieth century.
Vice counties were designed to:
- Have invariant boundaries over time.
- Split larger counties to provide more comparable units.
- Merge small counties for the same reason.
- Separate distinctive biological areas.
- Retain common boundaries with the civil counties.
There are over 100 vice counties in Great Britain (compared with 86 historic counties), and 40 in Ireland (compared with 32 historic counties).
Boundaries based on detailed digitisation from 1:10000 maps of the Ordnance Survey of Great Britain are available under the OS OpenData licensing terms from the UK National Biodiversity Network. I (SK53) am not aware of equivalent data being available for Ireland. The UK NBN confirmed (in an email to User:EdLoach) that it is OK to use their data in the same way as it is OK to use the OS OpenData.
Vice Counties should be mapped using a boundary relation, using boundary=vice_county. In many cases the boundary will follow other features (rivers, coastline, administative boundaries), but when a new way is required the boundary=vice_county can also be applied to that way. They are not administrative units so must not have an admin_level tag. They will only be rendered on specialist maps, and should not be used as proxies for old administrative units, not least because the boundaries are rarely co-incident (e.g., VC50 Denbighshire includes Maelor, whereas Maelor historically is an exclave of Flintshire).