Ads rely on cleaver imagery to hook the viewer. So when a media org (bbc) reports the image without a mask (and even enlarged it, high-res), they're in effect pushing the ad to millions of viewers.
PR companies very cleverly use traditional media (often outdated) to do their work — for free/close to nothing! Great hack.
Smoking ads are banned by the govs in many countries, including the UK (article) therefore, it's highly unlikely that the PR firm didn't expect it would be banned... yet, the bbc took their bait, in my opinion.
BBC could've have blurred the cigarette, or pixelated the image and then provide a 'Click to see the Original' feature for viewers that want more proof.