ΔE 12.5, fair: the same colour family, but not a straight swap. UK BSC is a little lighter, more saturated, cooler than Thar Brown.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). UK BSC is a little lighter, more saturated, cooler than Thar Brown.
The same difference applies the other way round: Thar Brown is a little darker, more muted, warmer.
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 Thar Brown on the colour wheel See UK BSC on the colour wheel
All matches: Thar Brown equivalents · UK BSC equivalents