ΔE 14.3, fair: the same colour family, but not a straight swap. Stormvermin Fur is a little darker, much more muted, warmer than British Brown.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Stormvermin Fur is a little darker, much more muted, warmer than British Brown.
The same difference applies the other way round: British Brown is a little lighter, much more saturated, cooler.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See British Brown on the colour wheel See Stormvermin Fur on the colour wheel
All matches: British Brown equivalents · Stormvermin Fur equivalents