I forget about numbers above 70 when it comes to coursework. In my department (history of art student, by the way), if you've got a first/70 you've done exactly what they expected of you for that question. The number following the 7 is how much more you've impressed them, pretty much.
The highest I've ever gotten was 82, and that was SO GENEROUS. I almost cried with joy. I loved that lecturer.
My boyfriend did a computer based undergraduate course and the highest he ever got was 94. If I got a 94, I would probably pass out.
With humanities there's sort of no right and wrong, just good and bad arguments, and whether the lecturer feels like agreeing with you.