I've seen that the majority of Band 6 group devised pieces deal with a political issue of some kind. Could that possibly be a factor in a high mark?
I don't think this is necessarily a factor in the sense that I don't think a marker is purposefully bumping up the marks of those that deal with these issues. However a lot of these issues are thematically really rich, and can be explored (or exploited) really evocatively through theatre, and thus are prime for a great GP. Along with this, if done well dealing with relevant and relatable concerns that the audience (your markers) may also be experiencing also can leave a more powerful impact. Thats why its often recommended to avoid dealing with subjects like teenage angst etc, because it's just not going to be relatable to your maybe 50+ year old marker!
That being said, if it is dealt with poorly - whether that be just a lack luster performance
or being potentially too controversial/offensive - you can still get marked down. Overall they're marking on your ability to translate ideas through theatre effectively - whether that is political or not.
Good luck
Susie