Pound at five-and-a-half-month low as Johnson leads, Aussie vulnerable

TOKYO (Reuters) - The British pound on Tuesday languished near this year's low on rising worries Boris Johnson, the front-runner to replace UK Prime Minister Theresa May, could put Britain on a path towards a dreaded no-deal Brexit.The Australian dollar is also at its lowest levels since the flash crash of early January, hit by growing expectations of another rate cut by the country's central bank and by the spectre of a further slowdown in China - Australia's largest export market.The yen and..