We didn't realise when we bought ours (August 2009) how rare these footprints were. We got one from W.M. Camping, Herne Bay, Kent (www.wmcamping.co.uk/acc2-09.php#). They will also send orders out by courier (for £12.00?), but check with them first for costs.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.