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"Eristalis intricarius is a furry bee mimic, superficially resembling Merodon, though Merodon have all black leg tibiae, as opposed to partly yellow."
The partly yellow tibia can luckily be seen well in my photo so I agreed with this ID, thanks.
Paul Seligman. Flickr: http://www.flickr.com/photos/paul_seligman_cardiff/collections/721576087...
Lat/Lng: 51.4593, -3.1765
OS grid ref: ST183740
Park but with some wild areas alongside River taff