ΔE 14.7, fair: the same colour family, but not a straight swap. Field Green is a little darker, more muted, warmer than Niblet Green.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Field Green is a little darker, more muted, warmer than Niblet Green.
The same difference applies the other way round: Niblet Green is a little lighter, 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 Niblet Green on the colour wheel See Field Green on the colour wheel
All matches: Niblet Green equivalents · Field Green equivalents