The images above were sent to me by Keith Noble recently. Three of the photos are of Nomada male bees that apparently attacked a social wasp that came too close. They look like the Broad-banded Nomad bee, Nomada signata, from the photos and Keith has identified them too. This cleptoparasite will use the nest of Tawny Mining bees, Andrena fulva. Nomada signata, was assessed as Vulnerable (RDB2) Falk, 1991.
This was an interesting observation, especially as the social wasp will be larger than the males and presumably is a female with a sting. The male Nomada do not have a sting, making this a risky interaction for the bees.