A very placid individual that allowed me plenty of time to take photographs.
No interactions present.
There are four likely options all around 5-7mm in length and are hard to ID without a specimen. They are: cupromicans, leucopus, morio and smeathmanellum. So it's unlikely that you'll get further, however your photos are very good so somebody may have a stab at an ID. If I were to make an educated guess I would go for either morio or smeathmanellum.
Thanks for the quick responses! Great to know what is visiting my garden.
Lat/Lng: 51.4484, -0.343
OS grid ref: TQ152734