What made these little mud pots?

What made these little mud pots? - UK and Ireland : Found this exquisitely made little mud pots on the underside of a chair. What could have made them

Found this exquisitely made little mud pots on the underside of a chair.
What could have made them?
I’ve looked up potter wasps and mason bees, but I couldn’t find a good match that’s consistent with my location.
08 Aug 2019
Bob_minty