There will have been a few red, amber and even green faces at Tesco HQ this week, the way the news agenda has gone.

Facing hefty fines following a raid on its dotcom store by the UK Border Agency, accused of manning it with the help of illegally employed immigrants and expecting a probe by government privacy bosses over accusations of lax security on its website – its PR team has had plenty to keep them busy.

But the third big story – its decision to support Andrew Lansley’s plans for traffic light labelling – is the one to stop observers in their tracks. It marks the latest twist in one of the longest-running disputes in the industry.

After an unsuccessful trial nearly a decade ago, Tesco has remained steadfastly opposed to traffic lights – until now. Former boss Sir Terry Leahy was among the most entrenched opponents.

Following the lead of bitter rivals Sainsbury’s and Asda with a combined system of traffic lights and GDA labelling is yet more proof that a new era has truly begun, under the more pragmatic approach of Philip Clarke.

Tesco says its own research has showed customers are “more sophisticated” than in the past and can now cope with a hybrid system as they seek to make healthy choices.

But Clarke will surely have also had one eye on the publicity gained by Sainsbury’s when it was singled out for praise in a recent BBC Documentary, while the programme makers accused the likes of Tesco of killing off plans for traffic lights and putting profits before health.

While the Department of Health lacks the power to impose a uniform system, Tesco would have been exposed to accusations of feeding the obesity epidemic had it continued to swim against the tide of NGOs and government advice.

Tesco is not alone in U-turning on this. When The Grocer revealed in May that government plans for traffic lights were back on the cards, it represented an about-face for Lansley, himself previously an opponent. It would have been interesting to be a fly on the wall during talks between the two in the past few months. Now Morrisons – which has also opposed traffic lights – is at risk of appearing isolated, unless it too changes tack.

Furthermore, Tesco’s decision poses a huge dilemma for suppliers, many of whom believe traffic lights demonise their foods in a way that the more nuanced GDA figures do not. The FDF has long considered traffic lights misleading, but positions on health have changed at lightning speed in recent months. Just witness the backtracking over minimum pricing on alcohol.

retailers and suppliers realise they must be canny about which battles to fight.