@amiessmacro it was noticibly smaller than the other Vespertilios that were around, and it doesn't have the horizontal dark/light across the rear of the abdomen like the other females I saw. Could it be a younger one which hasn't developed the usual pattern yet?
Is definitely female M. vespertilio. Within this sp. there is distinct size variation that has been noted but not documented. The female 'rockhopper' is a similar size but totally different in colouration; more rufous/brown through to ochre. The two spp. Co-exist in similar habitat.