Hi, I'm sure I didn't say I had tried everything but had found that the two suggestions (another dog to encourage her and gentle but firm coaxing) werent having the desired effect as she was disinterested in the other dog walking with her and was prepared to snap when pulled forwards or handled in a way that coerces her.
The speculation on her past treatment came from the rescue centre and I have no idea what might be going on in her doggy mind but personally I think she is trying to call the shots over things she dislikes (either from fear and uncertainty or just plain stubborness).
A long wait and plenty of patience is what has got her home when she has done this!
I am following the suggestion of using the lead around the house which is working well until we head for the front door or step more than a couple of paces from the back gate. I'll be persevering with this one and will be combining it the suggestion to get her to stand and move off.
When she is a little more trusting I will try using a harness with her - at the moment this is a non starter as she will sink her teeth into your hand when you try to do it up. I'm not for giving in to this behaviour but I am not sure if I will be trying to tackle too many problems at once by using the harness at the moment - it makes the whole walking experience unpleasant for both of us when it ought to be fun and enjoyable.
Thanks again for your ideas - I'll let you know how we improve!