A man carrying a Samurai sword was stopped by police in Mitcham.
Police officers stopped the smartly dressed man, who had the weapon slung over his shoulder, in Cricket Green on Thursday, August 14, at 4.41pm but he was not arrested.
Carrying a sword in public is usually a serious offence.
In 2008 Mitcham man Gary Kelly was found guilty of manslaughter after stabbing another man through the heart with a sword in a row over a football.
A police spokesman said there were sometimes carrying a sword might not be an offence, if there was a lawful authority or 'reasonable excuse'.
He said: "A reasonable excuse might be you had just bought it and were taking it home, you were on your way to a martial arts event or you were taking it for repair.
"Whoever the officer was, he must have thought the explanation given was satisfactory and did not need to make an arrest."