Well, this is interesting. I have a 90% complete grid, I think I have worked out one of the modifications.....and I still have no idea what's going on! It probably doesn't help that I don't have the ODQ. Am I likely to have heard of the originator?
It might help if someone could advise if 30d is something that happens when eg Oxford colleges race on the water. (Even if I'm right I can't see the parsing!).
Ah well, onwards...slowly....