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If you click through to the full size photo, the tip of the antenna on the left of the photo (which is the right-hand antenna from the fly's perspective) shows the characteristic shape for R.scolopaceus - the third (outermost) antennal segment is drawn out to a point (NB look at the yellowish segment itself, not the blackish, thread-like arista that extends from the segment).
The much rarer R. strigosus has this antennal segment rounded.
Entomologist and biological recorder
Lat/Lng: 52.488112, 1.019497
OS grid ref: TM051920