ΔE 9.5, close: similar, with a visible difference side by side. Middle Stone is a little lighter, more muted than British Uniform Lights.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Middle Stone is a little lighter, more muted than British Uniform Lights.
The same difference applies the other way round: British Uniform Lights is a little darker, more saturated.
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 Uniform Lights on the colour wheel See Middle Stone on the colour wheel
All matches: British Uniform Lights equivalents · Middle Stone equivalents