ΔE 15.8, loose: different enough that you should pick on purpose. Sky BS381C/210 is a little darker, more saturated, cooler than Wraithbone.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Sky BS381C/210 is a little darker, more saturated, cooler than Wraithbone.
The same difference applies the other way round: Wraithbone is a little lighter, 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 Wraithbone on the colour wheel See Sky BS381C/210 on the colour wheel
All matches: Wraithbone equivalents · Sky BS381C/210 equivalents