No interactions present.
B. ruderarius, apart from being rather scarce and not known recently from that area, has a red tail.
recording wildlife with The Recorder's Year on www.hbrg.org.uk/TRY.html.
It did have a red tail although it was very hard to photograph !, to fast
That is difficult to explain. The red hairs on ruderarius are actually quite inconspicuous and fringe the pollen basket. Despite the lack of focus, this bee seems to have a large brush of hairs, which is not compatible with a bumblebee. You might have had red-tailed Bombus lapidarius (black with a red tail) as well as A. plumipes (black) alongside each other.
I was lucky enough to have a B ruderarius in my garden (and accidentally photographed it, without realising).
Lat/Lng: 52.0364, 0.134
OS grid ref: TL464397