More information is available on the British Scathophagidae Recording Scheme website here:
The species status is notable but that is likely to change as it seems to be increasing. It is probably an introduced species, coming in on imported bulbs. The first UK records were in 1965.
I would be interested in hearing from others who have found it in Northants. It is fairly easy to identify, having the rounded head typical of a Scathophagid, brown body with dark thoracic stripes; two rows of spines below the front femora and one row below the front tibia, giving a mantis-like appearance. It has dark shading over the cross veins and wing tip but this shading can be very feint. Look for it on daffodil leaves where daffodils are well established such as in parks, mature gardens and roadside verges.