Thanks San I'll take care with the roots. I have a C. panzhihuaensis which grows a wierd root structure with many nodules near the surface and just above soil level (I don't mean the caudex) which I've read somewhere is normal and part of the plants nutrient uptake.
I think I'll plant my revoluta in the ground next June with serious winter protection in mind. Despite being what I regard as a good sized specimen it was only £20 from a nursery who travel to Tatton every year with dozens just like it. It'll look amazing next summer if nothing else