OK,
here's another for the slueths...
I've two pieces with this mark and it's a bit clearer on the other but I cant find it in all the boxes at the moment so will post this for now.
Thrown stoneware, high fired running glaze, 10cm diameter, 7cm high.
Painted mark = circle with cross and dots inside, attached C, conjoined 73 (date I think) and signature (I'll hunt down the clearer one asap)
I dont believe it's British, my guess is French or German?