RAF Light Aircraft Grey BS381C/627 vs Grey Seer

How close are they?

ΔE 9.3, close: similar, with a visible difference side by side. Grey Seer is a little darker than RAF Light Aircraft Grey BS381C/627.

Can I use Grey Seer instead of RAF Light Aircraft Grey BS381C/627?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Grey Seer is a little darker than RAF Light Aircraft Grey BS381C/627.

Can I use RAF Light Aircraft Grey BS381C/627 instead of Grey Seer?

The same difference applies the other way round: RAF Light Aircraft Grey BS381C/627 is a little 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.