Odd particle edit behaviour

Hi folks.

When I enter particle edit mode on a mirrored mesh, I only see particles on the mirror image side of the object, not the editable side of the object. Is this normal?

Then when exiting particle edit mode I see the smooth/comb effects have only taken hold on the mirrored face. This is a bit of a pain.

So I applied the mirror modifier and now the particles behave completely differently on either side of the mesh, to the extent that half of them have disappeared!

Am I missing something?