Pret a Manger sources the salmon trout (known as rainbow trout in England) for its Deluxe Sushi box from Chile, where it is farmed. It is frozen in Chile and shipped to England. An independent supplier, Taiko, assembles the sushi in London before it is distributed to Pret a Manger.
The company has already changed the information on its website after the Sunday Telegraph wrote a lengthy feature about it yesterday, removing the 'spankingly fresh' claim.
The newspaper has launched a campaign to make food labelling easier for consumers to understand, and wants rules allowing producers to label food as 'British' to be tightened up.
Pret a Manger's communications talks a lot about how its food is sourced, saying it only sells dolphin-friendly, line caught tuna and that it almost never air freights any of the fruit or vegetables used in its products.
The Chilean fish farm industry, however, has been criticised by environmental campaigners because it very intensive. Salmon, in particular, have been affected by disease, although the company that makes Pret a Manger's sushi, Taiko, pointed out that it only imports salmon trout and not salmon.
Pret a Manger's website has a section devoted to sustainability but at the time of writing it makes no mention of how it sources its sushi.