Alarger than normal hover-fly
No interactions present.
Often seen on Succisa pratensis and sometimes known as the Bog Hoverfly.
But really shouldn't be called that, as the name has been applied by different people to two different flies.
It is Sericomyia silentis...and can't be confused with anything else by that name!
My Flickr photos...
Lat/Lng: 56.535, -4.245
OS grid ref: NN620403