The banded general soldier fly is of the ‘big five’ soldier flies (4 Stratiomys species plus Odontomyia ornata). Easily distinguished from O. ornata by the long antennae. It is one of two boldly marked yellow and black.
Stratiomys potamida is a spectacular large yellowish soldier fly of wetlands, including fens, damp heaths, damp woodlands, alder carr and coastal landslips and ravines. Records are widely dispersed in England as far north as Northumberland and also into south Wales. Larvae develop in the mud of seepage marsh and away from seepages, in the mud and standing water amongst vegetation at the edge of ponds and ditches.
They probably take three or four years to develop and seem able to tolerate quite severe drying out of sites in summer droughts (Falk, 1991a).
This one was seen in the gardens of Chiswick House in July 2020. Here is a link to a garden spider.