Slightly off topic but practical, if you trade as anything other than your own name and accept cheques in payment payable to your trading name then you must register that trading name and show proof as otherwise your Bank will not accept those cheques for lodgement to your personal account.
Business names are a legal requirement if you are trading as a name other than yourself. Does not give any protection at all and name is available for use by other.
Obviously if Richman is still trading then he can have a pop at you under passing off or some other IP infringement if you trade as Richman.