The idea of an insurance policy you have to keep secret reminds me of chancel repair insurance in England. Because of various arcane feudal remnants, the owner

The idea of an insurance policy you have to keep secret reminds me of chancel repair insurance in England. Because of various arcane feudal remnants, the ownership of certain pieces of land comes with an obligation to pay for repairs to the local church building. This can be very expensive, so buyers of land where there is a possibility that this liability might exist are advised to buy insurance to cover it. This insurance is very cheap, because it's quite rare for this liability to be discovered- usually it's a one-off payment of about £30-50 on buying the property. It is, however, a standard term in the policy that it is void if you tell anyone that it exists. The reason for this is that, while the liability for repairs to any given church originally attached to one piece of land, this land has often been subdivided. In this case, the owners of all the pieces of land are jointly and severally liable for repairs- in other words, the church can go after any one of them for the full cost. And, of course, a property owner with insurance is a more attractive target as they're more likely to be able to pay, and to do so without making unpleasant headlines about how they might lose their home because of an obscure mediaeval law.