We usually buy the Nivea kids' SPF30 sunscreen as it's water resistant and easier to use than many of the brands (though expensive). My local Tesco Extra (Solihull) is clearing their remaining stocks at massive reductions such as the one quoted above. Other types also on offer.
I imagine it's a case of 'while stocks last' but it had a proper yellow shelf label so may well be a national deal. Good luck!