That's a great help; thanks - and thanks for the advice about the bogs / tussocks.
Think this one might be better done if we get the usual long dry spell in late spring, to dry up the bogs a bit.
Well, I lost patience waiting for a long spell of dry weather and ran the Bannisdale Horseshoe yesterday. It was indeed tussocky and very wet underfoot (but this wasn't really a problem in fell running shoes, although it made for slow progress and the run took me 3 hours). Really enjoyed it and just wanted to thank those folk above who took the trouble to provide valuable information.
I used the Wainwright (Outlying Fells book) route, starting from the parking spot he suggests not far from the A6. 75% of this was blocked by piled up gravel, so only room for one vehicle. I note (from another internet source) that the potential alternative parking spot near Dryhowe Bridge was also almost obscured by piled gravel. Just saying, so that future visitors are aware (and have a range of alternatives for parking ready).
I found this route to be a paradise of peace and tranquility. Didn't see a single person all the way round (even though it was weekend and a sunny afternoon). I also didn't see a single piece of litter, so the plastic bag which I always carry in the bum bag (for stuffing litter in) remained unused for once.
There are other potential horseshoe walks / runs in the Shap fells area; think I'll be back for more before too long . . .