suddenly loads of these have joined the hordes of drone flies on the ivy blossom.
Thought may might be Autumnalis
No interactions present.
Not sure what it is, but Cluster fly usually refers to Pollenia, rather than Musca.
My Flickr photos...
It is Calliphora vicina.
Lat/Lng: 55.9625, -2.4015
OS grid ref: NT750744