the Chapel Street problem goes straight up the corner, like an overhung arete. I seem to remember that there's an undercling of some sort in there, and possibly a thin crack where the two prefab pieces meet. However I haven't seen this thing for over a year now so I might be wrong, anyway I don't know anyone who's made it yet, so best of luck.
Keeping on the subject, there's that massive grit wall in Allestree, up Duffield Road, just before you get to Palm Court Island. As you leave Derby it's on your left and is someones garden wall, but the traverse goes on forever (well, about 30/40 metres). Then theres the grit wall on London Road where the road goes over the train lines, made considerably easier on recent years by the traffic calming measures. There's a few problems on St Werburghs and the power station thing behind it, and the monumental straight cracks on the retaining wall below Radio Derby. They're only one move but a bad fall could see you bouncing down the hill into the ring road!
I'd be well up for an assault on the cathedral but I won't be back there until this time next year. If you get in the paper post up a cutting, and if you want to wait I'll be ready on July the 1st, 2005.