Liam is a brewer. He has started to sell his beer under the brand name 'Duffa'. Liam has chosen this name for its resemblance to the name of the fictional beer 'Duff' in the television show The Simpsons. Liam has altered the name slightly to give it an Australian twist ('duffa' is Australian slang for a person who makes lots of mistakes). The design of the Duffa can is very similar to the Duff beer can seen on The Simpsons. Liam wants to register the name Duffa as a trade mark. Twentieth Century Fox (the producers of The Simpsons) already owns a registered trade mark 'Duff' for use as a beer or alcohol brand however, it has never used the mark since it was registered (in 1996).

(a) May Liam register the name Duffa? Explain your answer, considering the name only.

(b) Should Liam keep selling his beer under the name Duffa (whether or not he may register it as a trade mark)? Explain your answer.