I am hoping that's it, will look if I can split the load on the board, split across two rings, but I think (can't remember) probably the same rcd, not mcb tripping. Rcbo's on the lighting circs if I recall.I would say with the longggggg boil you have heated the mcb/rcbo and it’s thermal overload properties have kicked in
As its the rcd, I need to investigate if my recent rat problem has anything to do with it, need to find my multifunction.