"56. Just as the starting point where there is sole legal ownership is sole beneficial ownership, the starting point where there is joint legal ownership is joint beneficial ownership. The onus is upon the person seeking to show that the beneficial ownership is different from the legal ownership. So, in sole ownership cases it is upon the non-owner to show that he has any interest at all. In joint ownership cases, it is upon the joint owner who claims to have other than a joint beneficial interest."