Dave Venables
Can’t find any sources supporting the DE6 4NA Radbourne Common postcode https://www.openstreetmap.org/way/467142959 

DE6 4LZ Radbourne Lane for Radbourne Hall and the farms on Radbourne Lane made sense historically before the new houses were built. This is supported by Food Standards https://ratings.food.gov.uk/business/en-GB/352265/Hackwood-Farm-Mackworth where the address also shows Derby and by Hackwood Farm’s own Facebook page https://www.facebook.com/hackwoodfarmshop/ 

DE6 4LZ is not that helpful for navigation as the track directly from Radbourne Lane is no longer available https://www.openstreetmap.org/way/240880963  and Starflower Way https://www.openstreetmap.org/way/609758508    DE3 0FB Derby is more useful. City of Derby as OpenStreetMap has it feels correct despite the current DE6 Ashbourne postcode.
