ΔE 11.7, fair: the same colour family, but not a straight swap. Leather Brown is noticeably darker than British Sand Yellow.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Leather Brown is noticeably darker than British Sand Yellow.
The same difference applies the other way round: British Sand Yellow is noticeably lighter.
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 Sand Yellow on the colour wheel See Leather Brown on the colour wheel
All matches: British Sand Yellow equivalents · Leather Brown equivalents