When any store collects its wholesale bread delivery, it is safe to assume what much of this staple foodstuff will be used for, especially at this time of year.

Summer is when the art of sandwich making comes into its own, with lots of picnics and days out in the offing.

Of course, there are alternatives to making sandwiches at home, but it appears something fishy is afoot, (or maybe a fin). Either way, Subway is in the news for all the wrong reasons because a laboratory carried out tests on a tuna sandwich bought from the chain and found no trace of any tuna DNA.

It is true that this happened in the US, with a New York Times reporter acquiring the sandwiches from a Los Angeles branch. But Subway is famous for offering the same menus all over the world, so it may beg the question of just what people are eating.

Speaking to the paper, a spokesperson for the lab – which remained anonymous (to ensure their Subway loyalty cards weren’t revoked?) said: “There’s two conclusions. One, it’s so heavily processed that whatever we could pull out, we couldn’t make an identification. Or we got some and there’s just nothing there that’s tuna.”

Of course, it is only fair to note, as the paper did, that DNA is harder to detect after the fish has been cooked. Also, there are 15 varieties of tuna and the lab test only searched for five.

However, this is a serious enough issue, because the New York Times investigation was prompted by a recent lawsuit in California launched by two customers who claimed there was indeed no tuna in Subway’s tuna sandwiches.

All this seems a bit of a worry. After all, people have been catching and eating tuna for millennia. But if Subway is indeed substituting something else for it – a claim they deny – it begs a few questions.

The safe conclusion may just be that people should pop to the local shop, buy a loaf of bread, take it home, open a tin of tuna and get to work.

Assuming what’s in the tin is tuna, of course..