I have recently got a digital zoom microscope so I have been going through some of my specimens and running them through my key (Naturalists Handbook 24 Ants by Gary J. Skinner). I think that this is a Lasius umbratus queen but I also think there is a possibility of it being Lasius mixtus. In my key it states that L. mixtus do not have erect hairs on the hind tibiae nor slanting hairs on the scape. At first I thought my queen could be Lasius mixtus because it satisfied the key. I looked up some images of L. mixtus on AntWeb and the queen pictured there does have slanting hairs on the scape. So I am left a little confused.
Location - Lullington Heath, East Sussex, UK
Habitat - Chalk heath land, under a fallen post
Characteristics - Head width is roughly the same as the thorax with large mandibles. Small gaster. So a social parasite.
Size - 5mm
P.S Sorry for the nasty looking pin.