Bloody-nosed beetle

https://www.naturespot.org.uk/species/bloody-nosed-beetle

Being a parent of two bug-fascinated children feels like a crash course in entomology.
Tonight's task - to narrow down which of the 4072 Uk beetle species this one was.

At least it provides the option to add 'don't put that [Timarcha tenebricosa] in your mouth!' to the usual repertoire of sand/pebble/slug/mud/leaf/sandhopper/woodlouse.