Sadly, the Red-shanked bumblebee (Bombus ruderarius) species is gradually declining across the whole of the United Kingdom and is now only seen in Wales and the south of England.
It has been noted that they prefer expansive areas of grassland to forage and feat on but there have been sightings in other habitats. Their nests, however, will typically be in spaces of thick foliage or possibly just beneath the surface of the earth.
All three castes (queens, males and workers) are completely black with a pale orange tail. However, the workers and the queens display orange hairs on their pollen baskets so it is less complicated to distinguish these from the males. Plus, to make it even easier, the males of the Red-shanked bumblebee tend to have a yellow or grey collar and a hard to see grey stripe around their abdomen.
The Red-tailed bumblebee (Bombus lapidarius) is quite similar to the queens and workers of this bumblebee species. Although you can tell them apart by their long faces, smaller abdomen and red instead of orange hairs on their pollen baskets.
On the other hand, the males resemble the Red-tailed cuckoo bumblebee (Bombus rupestris) because of their dirty-yellow bands. On the plus side, this does make it easier to distinguish the males of the Bombus Ruderarius species from the Red-tailed bumblebee since they are less bright.
If you look carefully at them, you will notice that their banding pattern is akin to that of the Shrill carder bumblebee (Bombus sylvarum), however, the stripes are significantly darker on the Red-shanked bumblebee (Bombus ruderarius).
Like with any living creature, if you want to be completely sure you would have to conduct a DNA test. The good thing about these bumblebees though, is that you can have a gander at the genital capsule of the males to check the ID properly.