There were quite a few of these insects in an area of Tatton Park by the lake, and they seemed to relate to small holes in the ground prevalent in that area. At first we thought it was some sort of solitary bee, but web research didn’t come up with any matching images. It seems it must be some sort of digger wasp, of which there are 110 different species in the British Isles.
According to Buglife, digger wasps are solitary nesters, and the tunnels may be 30cm deep. They may also nest near to each other in colonies, which is what we saw in Tatton.