Large black bumble bee with red rump.
No interactions present.
I agree that this is most likely to be the red-tailed bumblebee Bombus lapidarius - the rarer Bombus ruderarius is very similar but given the time of year and location I think lapidarius is much more likely.
(By the way, when adding an identification you should be able to click on the "Get Recommended" button to fill in the scientific name if you wish; this can be useful for species such as the bumblebees, where the English names are not very widely standardised.)
Entomologist and biological recorder
Lat/Lng: 51.4, -0.4
OS grid ref: TQ1573