The Labour movement from 1972 to 1982 is basically one of the strangest things ever published about politics anywhere.
(But yes Schoolteachers, Doctors and Lawyers' positioning is close!)
The fact that some put so much faith in the Political Compass charts is downright perplexing.
It's literally one of the most poorly cited sites on the Internet. There's no indication whatsoever who runs it or makes these charts, even that they're Brits is only implied. And they even admit where they place the politicians and parties on the charts is just their guess because they didn't take the test. But at least half the questions on the test aren't even related to policies, just general attitudes that there's no way to discern. And they don't reveal their methodology at all. I'd say the burden of proof you're not just pulling numbers out of your ass is on the one making the claims, even if they're making nice looking charts with said numbers.
(BTW I just noticed that the SDLP are actually slightly to the left economically of Sinn Fein. There's another "LOL")