Here's my postmen, the Jacket for "regular" postmen in the 1930's looks a lot like SD but with some small changes you don't see on a 28mm figure. I used a Prussian blue for the blue and a royal red for the piping. Use WW1 German Jager for the 1910 uniform hat. WW1 british for anything else.
Here's some better group photos
Post Office Artillery
Post Office Rocket Troop
Masses of Postmen
Postmen and "Friend"
Mail waggon
In action
Best Wishes,
Bigglesmay