Obviously I can only speak for where I worked. Several of the guides were students (some of them did an extra unit preparing them to work as guides) and others worked in the Arts library part time or did some assistant/research work for the lecturers.
Right, that's helpful, it's (as you rightly guessed) BA, not MA. So that probably rules that out, think I'm going to have to trawl the OU careers board. It's all a million miles away from the work I'm currently doing.
I have an Art History/ Design History degree and I work in a museum but it is a difficult field to get into, not great pay and to get a paid job you usually need a reasonable amount of voluntary experience and possibly a Masters degree - I have one in Museum Studies.
70% of graduate jobs accept people with a degree in any subject - it's your work experience and what you've done alongside your degree that's important there. Your career doesn't have to relate directly to the degree subject you did, even if the career requires a degree. So, a more pertinent question question would be what do you want to do career wise? Unless you want to do something that requires a very specific degree, such as nursing or architecture, then you almost certainly can.