Hi Woody,
We stayed at Clumber in February and even though it was quieter than later in the year the Site Security was still patrolling in his LR at night and the offer of using the site lock-up for bikes was available. I know that there is still an issue with some local undesirables, but I would imagine that if you don't give people an easy opportunity to nick things (by putting things out of sight etc), then it is probabaly as secure as any rural site.
Neal