Hong Kong’s Security Bureau has apologised for an advertising blunder in its anti-drug campaign, after a banner in a railway station appeared to encourage the use of illegal substances when viewed from certain angles.The bureau addressed the issue in a social media post on Friday, a day after an internet user circulated a photo of the poorly placed advert at Tsim Sha Tsui MTR station.The banner was part of the government’s latest anti-drug campaign, featuring one of Hong Kong’s “Four Heavenly...