Ahhh, you noticed did you!
I'm pretty sure it was Andrena fulva nest... but I must admit I was paying more attention to the Nomada sp. sat outside (as at the time I didn't know what it was up to!). However, as you say, my pictures do look very like Nomada flava.
Thanks for your help Janet.
Tipping down with rain and looks like 5pm (at 9.30am in the morning!). Hope it's better where you are!
Jane