There has been much discusion on the Caravan Club forums regarding this subject, including advice from Lawyers who themselves are Caravan owners and fully aware of their Legal rights and responsibilities as set out in their contract. For touring caravans, there would have been the option for most people to simply cancell their contract as soon as this outbreak began, and remove their caravan from the site, either to a storage yard or onto their their own property, drive, or that of a relative or friend if needsbe. Whilever your caravan remains on the site, they are providing a chargable service, rather like paying for land that a leasehold property stands on as an annual fee, regardless of how much time the owner of the property actually occupies it for.
The virus in some ways could be seen as ' an act of God' as in no one individual can be held responsible or sued for damages caused by it in a court of Law. The only things that you may be able to claim back are the money paid upfront for the utility Bills such as Electricity, water, and other consumables you would have used should you have been onsite rather than at home, but even this would depend on the small print wording on the sites contract, and things like site maintainance, security, and their general insurance costs are not refundable whilst they still have your caravan on site.
Those with Static caravans are at a bigger disadvantage, any disputes with the site owners, or if the site owner was to be declared bankrupt due to this crisis, their pride and joy would need to be moved off site, and not only would this be expensive, but finding a site that would accept a static that they have not sold themselves is nigh on impossible, hence the likes of E-bay et al are full of secondhand Statics going for a song. There has recently been such a situation develop on one of the East coast sites in the Skegness area, and owners have been left many thousands of pounds out of pocket. In general, there is a fear amoungst owners of similar situations developing in the long term of sites closing down for good due to financial reasons brought about by this virus. Many sites simply will not survive due to loss of weekly revenue from hirers throughout the season, being asked to refund every penny of the annual site fees from caravan owners may end up being the final straw towards a sites perminant closure.
I appologise if l have not explained this very well, I am a caravan owner myself, and have been for many years, although I prefare Touring with my pride and joy, rather than staying at the same destination every time.