(Unfortunately I had to use the flash because of this little bat's position)

Notice the red dots - enlarged they are obviously mites of some sort.

The common pipistrelle (Pipistrellus pipistrellus) is a small pipistrelle bat whose very large range extends across most of Europe,
North Africa, southwestern Asia, and possibly into Korea. It is one of the most common bat species in the British Isles.
The common pipistrelle is the smallest bat found in Europe.
It is 3.5–5.2 cm (1.4–2.0 in) long along the head-and-body, with the tail adding 2.3–3.6 cm (0.91–1.42 in).
The body mass can range from 3.5 to 8.5 g (0.12 to 0.30 oz), with the wingspan ranging from 18 to 25 cm (7.1 to 9.8 in).
Its brown fur is variable in tone.
It is common in woodland and farmland but is also found in towns, where the females roost in lofts and buildings when rearing young.