Meriden definitely did have BNP and Green councillors from 2008 to 2010 - BNP in Chelmsley Wood, Green in Smith's Wood.
Chelmsley Wood ward voted BNP in 2006 and Green in 2011.
ah yes, knew about Chelmsley wood but wasn't sure if they overlapped
The current Dewsbury seat contains wards which had both BNP and Green councillors concurrently - BNP in Dewsbury East and Green in Kirkburton. At the time however they were not in the same seat, Kirkburton at that time being in Wakefield.
If the boundary proposals are adopted in Watford, that seat would be unique in having county council seats (as well as district council seats) that have elected BNP and Green councillors (South Oxhey and Callowland-Leggatts respectively), but the BNP councillor is no longer BNP and will no longer be a councillor either by the time that seat comes into existence (if it does)