Tagselling empty jam jars

Shoppers were left perplexed after realising a free jam jar in a big-name supermarket fetched more than a full one.Customers in Waitrose note that a jar of the store’s raspberry jam costs half that of an empty pot of the same size – £1.20 instead of £2.50.Smooth a jar of well-known Bonne Maman strawberry conserve, also obtainable in the chain, was valued at just 15p more than an empty...