Not the best photo, but this was taken on my bathroom window in Loughborough. I have also seen one in my garden.
The body is black with a single fawn coloured band.
The wings are normal translucent except they have the same fawn coloured band followed by a smaller black band at the top that corresponds with the body - as if someone sprayed a stripe across it.
The fly size is similar to a large blue bottle
Thanks in advance
This is a Pellucid Hoverfly - Volucella pellucens https://www.naturespot.org.uk/species/pellucid-fly
how dangerous to bees are they - we have bee boxes
Not at all, they are not predators.