The British insignia are the third in Scale Specialties "N" Scale (1/160) decal series.  The Spitfire IX, Hurricane, P-40, and P-51 all used these same sized insignias, and although designed for use on Minifigs aircraft, some of the smaller sizes will fit 1/144 scale aircraft (as a customer told us).

This sheet of decals stands by itself, although 160AC-004 provides a fully completed Spitfire or Mustang - with the Squadron Codes, Serial Numbers and tail bands.

Printed by Microscale, Inc., with consultations with Super Scale have produced some of the finest detailed small-scale decals available on the market today.
 

British insignia for Spitfire IX, HURRICANE, P-40 and P-51 wing and fuselage insignia and tail and fin flashes 1942.
Catalogue Number 160AC-003 - 4 3/4" x 3 3/4" - priced at $5.75.  (Click here to view decal)