The wasp was moving slowly over an area of sandy bank. It was about 7mm in length.
No interactions present.
One Chrysis species (C. ignita) parasitises mason bees - (mainly). Any bees's nests around?
Thanks to all for the help with this one. Having looked again at the BWARS site, this time at Hedychrum niemelai which seems to have the same colour pattern for the thoracic segments as the one I photographed. Its usual heathland habitat is also similar to where I took the photo - so a strong candidate!
There were Anthophora bimaculata nests in the area.
Lat/Lng: 49.7682, -7.5559
OS grid ref: SV001001
Sandgate is a heathland reserve with sandy areas amongst Erica and Calluna. There were nest of Anthophora bimaculata in the immediate area.