Later, I rode in the large arena - not wholly successfully, i have to say, after about 20 minutes she decided not moving was good, and was ignoring my leg - now, i don't want to go back to kicking, which is just counter productive in the long run, so decided to see if i could sit her out - also thinking that if someone arrived, which happily they did, they could fetch me my schooling stick which was, unhelpfully, in the stable.
after about 10 minutes, my prayer was answered, RI turned up (she mucks out a friends horse sometimes) and brought me my stick - one tap, and molly moved.
after that, i concentrated on getting the walk right and getting her moving into the contact, ended up doing lots of 10 - 15 metre circles; could only get half round the arena before we lost it!
when i put her away, turned out a lot of the problem was that she needed a wee - she's one of those that doesn't when you're on her! ah well.