I removed an old path of paving slabs from the garden the other day. They were just laying on top of the soil and not entirely surprisingly underneath almost every single one of the slabs was a heaving mass of ants and their white grubs. Of course the minute I exposed them they started rushing to take their grubs off down their tunnels to safety, but it took them over half an hour to do so.
The ones above are probably literally Black ants, and the ones below Yellow meadow ants. More information on the UK's native ant species is available via h2g2 or antnest.co.uk.