Dark egg green??

There are actually two colors involved here.  Duck Egg Green was an unofficial name given to the RAF color known as Sky.  It was used on the undersurfaces of day-operating combat aircraft in the early stages of the war.  When the camo was changed from dark green/dark earth to dark green/ocean gray, the Sky was replaced by medium sea gray.  Fighters kept a Sky band around the fuselage just forward of the stabilizer for most of the war.  So it was an extenal color.

Cockpits were painted, oddly enough, Cockpit Green, a color sort of like green zinc chromate, but without any olive cast to it.  I believe MM makes both colors.  If you can find a listing of their products by nationality (some hobby shops have their MM paints arranged that way) you should find both.  I usually use Humbrol, so I'm not sure what MM calls their colors.  Humbrol, for example, now calls Sky,  Beige Green.

Jolly good show, stiff upper wicket and all that.