Nomad Bee / Cuckoo Bee

Cuckoo bees get their name from birds with a similar habit.
There are several species of bee that have resorted to laying their eggs in the nests of other bees and this is one of them.
I am as certain as I can be that this is Nomada goodeniana which is the most common of the UK's Nomad bees.  It preys on the nests of solitary mining bees such as Andrena nigroaenea.