Hi IAIN, looking in my books you have a Group 3 Clematis, which means any pruning and moving is best done around spring time.
Yes it can be moved, with some care, cut all stems back to a healthy pair of buds 1m(3ft) above ground level in march.and remove any damaged stems, give the plant a drink before moving it, dig around the rootball at least two feet from the main stem, then dig a hole the same size and add plenty of compost into it, add some fish blood and bone,well water for a couple of weeks then you should see new growth
i expect some true experts will tell you more,and fill in any gaps i missed out
hope this helps
windy