Interesting that such greats as Tesco and M & S should get it wrong, or did they? The law relating to claims for sun care means that if a product tests higher than the next step (SPF20) then it should be labelled as SPF20. Two points, at this level of protection the chemicals to get the extra 5 becomes exponential, these chemicals are very expensive, do you seriously think ASDA would throw superfluous chemicals at a £3 product? Second point what this suggests is variability of testing - every year Which? do this. Every cosmetic product that makes a claim has to have independant testing data to support those claims. And every year no one takes any notice of their article.