BEDFORD (REUTERS) - They are a photographer's delight and a spin doctor's nightmare - advertising posters with a message that can inadvertently ruin a carefully planned election walkabout.

Labour opposition Jeremy Corbyn was the latest victim as he campaigned in Bedford, central England ahead of next month's national election.

Whilst promoting his plans for the National Health Service, Corbyn was snapped walking with party members under the words "Urban Decay" in capital letters on a shop window, advertising a US cosmetics brand.

Senior figures from the ruling Conservative Party have also been tripped up: pictures of finance minister Philip Hammond and Brexit minister David Davis under a poster apparently reading"hell for you family" were circulating widely on social media on Wednesday (May 3).

The full slogan behind them had been: "Corbyn: No bombs for our army, one big bombshell for your family." But the biggest photographic danger for election candidates remains pictures of them eating.

On Tuesday, photos of Prime Minister Theresa May awkwardly eating chips on the campaign trail in Mevagissey, Cornwall dominated British media.

They were described by media as this year's "Ed Miliband bacon sandwich incident," referring to an infamously unflattering photo of the former Labour leader looking bemused as he chewed on a bacon sandwich in the lead-up to the 2015 election."We should talk ..." Miliband jokingly tweeted the prime minister on Wednesday after her chip-eating photos emerged.