<<The most common way to insure personal property is as a rider on home-owners insurance, which is pretty reasonable.>>
I'm afraid that's not often the case in the UK. There are few policies that allow this flexibility and those that do are very expensive. That's rip off Britain for you when I can and actually do insure my car for less than it costs to insure my camera equipment! Part of the problem is that most policies are obtained by on-line comparison sites and these have no flexibility to add named valuables on. One can go the non on-line route, but once again this is very expensive in my experience. It seems that UK insurance companies want our money very quickly, but additional options are purposely made clumsy to obtain. Getting paid out for a claim can be equally as torturous as I have found to my cost!