Monomorium

Tiny ants. Two sizes photographed - 1.5 - 1.7 mm and 2.5mm for the larger one. Double noded petiole, no propodeal spines and triple clubbed antennae with no teeth on clypeus suggests monomorium to me.

Edit 1: It has been identified by Melanie (Melde M), Peter Slingsby and Peter Hawkes that this observation has two species of Monomorium. The last image (of the second species with length being measured) has therefore been removed and placed at this node: http://www.ispotnature.org/node/805536, where I have done more extensive photography of the second smaller species of Monomorium. A select number of 5 images from that observation was moved to the end of this observation (last 5 images).