The AntsCanada Ant Forum's

My friend is looking for messor barbarous in the uk I told him that they are not native to the uk and he keeps looking, he finds someone selling in the uk near him who is a mrmycoligist and owns several different species of ants. can he legally buy messor (a non native ant species) in the uk if he is not shipping the ants.

While if is ecologically irresponsible, yes.

Yes, in Europe most ants can be traded legally (with a few exceptions).
Also the UK has a particularly limited amount of native genera (no Camponotus, no Messor) that makes it hard to find anything that is not Lasius, Tetramorium, Formica or Myrmica.

Not necessarily. There's over 60 species present.

Yep, and most of them are either Lasius, Formica, Myrmica, Temnothorax or Tetramorium. Although that doesn't necessarily say something about their availability (like there's only few Tetramorium species but they're probably very common around human settlements). But many common european genera are missing entirely.

Most likely because it's an island.