Labelled map of Royal Mail postcode areas of the United Kingdom and Crown Dependencies with insets for Manchester and London conurbations.
Equirectangular projection with latitude stretching 170%, WGS84 datum.
Geographic limits:

Main 1:5,000,000 map:
West: 11.00W
East: 2.20E
North: 61.00N
South: 49.00N
Manchester 1:3,000,000 inset map:
West: 3.30W
East: 1.10W
North: 54.10N
South: 53.10N
London 1:1,000,000 inset map:
West: 0.50W
East: 0.30E
North: 51.70N
South: 51.30N
Derived from Ordnance Survey OS OpenData.

Postcode area boundaries within Great Britain derived from Voronoi polygons of OS Code-Point Open unit postcode median coordinates (with coastline clipping and minor adjustments to avoid spurious detached polygons).
National borders and coastline data derived:
from OS Strategi for inset maps
from File:United Kingdom location map.svg (version 2011-01-11T22:14:29) for main map coastline and Ireland border.
Richardguk