hi, and welcome!!
Yes, as abyeb
says, the round head and a heavy jowly appearance around the whisker pads, those big eyes, the dense fur, stocky/chunky bodies and legs - British shorthair for sure.
and they are fabulously stunning cats!!
Oh goodness - 1CatOverTheLine
, can you describe the difference - this is so interesting! Is it that the face is flatter in profile?
EDIT, no, reading a bit sounds like Scottish straights are a bit of a conundrum? But in any case these darlings have British shorthair in the lineage - yes?