Yes SL I am being pedantic but for a reason.
You mention the car park signs. Many of those signs have no legal strength following a court ruling some years ago. A customer's claim for loss whist his car was in a car park was upheld, but the detailed reason I believe was to do with the car parks access control by barriers. You may note that most car parks do not have barriers but are pay and display.
Many caravanners are being told by their insurers to use storage sites under the CaSSOA banner. These sites all claim to offer a secure place to store a caravan, and access to the sites is controlled by gates and other security measures. Not only do these sites use the word security they charge their customers a premium service rate. Some insurers will reduce premiums on the pretext that you are using a secure site, but the reduction does not offset the additional costs of using the sites.
If these sites have their way, then if you suffer any sort of loss whilst the caravan is behind their 'secure' gates and fencing, they can wash their hands of any responsibility, but why should they be allowed to do this?
Consider:- The sites are private property and they have access control, and that means the site owner decides who can be allowed in. This also means that the site owner has a responsibility to prevent unauthorised persons gaining access.
If an unauthorised person does gain access, then the site owner has failed to provide the service they are contracted to do.
Also if only authorised persons can be admitted, then the site owner has deemed such persons to be a fit and proper people to have access. As the site owner has control, all persons admitted are under the direction of the site owner, just as if they are employed, and as with any employed person the actions of the employee are the responsibility of the employer or in this case the site owner.
Therefore if any authorised person damages or removes property , the site owner is responsible. It is then up to the site owner to seek redress against the offender.
Banks take responsibility for your money left with them, Carriers accept responsibility for parcels they transport. Garages have to accept responsibility for customers cars left with them for service or repairs, Why should Caravan storage yards be different.
Clearly they should accept the same risks that other storage and carriage businesses have to cover.