Which High Street prawn sarnie has 44 and which one has a measly 19?

As M&S claims to launch Britain’s best, our scientific test reveals ...

THIS was the product that helped to kickstart a lunchtime revolution: the Marks & Spencer prawn sandwich.

In 1980, the retailer sold Britain’s first pre-packaged sandwich — an entirely novel idea at the time. Shortly afterwards, it launched the prawn variety, which was to become its most popular.

Since then, British consumers have fallen in love with the convenience of pre-made sandwiches, buying about four billion every year, with many of us popping a vegan tofu and coleslaw wrap or parma ham on focaccia into our shopping basket as a matter of routine.

But it is the prawn sarnie that remains pre-eminent.

And earlier this month M&S released what it claims is its ‘Best Ever’ prawn sandwich, bursting with ‘Atlantic cold-water prawns and meaty Honduran warm-water prawns’ along with a Marie Rose sauce flavoured not just with Tabasco, but brandy, too.

It’s a bold claim. But does it stand up to scrutiny?

We investigated by analysing all the prawn sandwiches sold in the leading supermarket and lunchtime chains, comparing their nutritional content as well as the prawns.

We didn’t just count the number of crustaceans, either — we also wiped off the mayonnaise, then weighed them.

Weight of prawns as a percentage of a sandwich’s overall weight is probably the truest measure of the filling’s generosity.

To be extra thorough, we brought two of every type and averaged out the weights.

CHEERILY CHEAP

ALDI Eat & Go prawn mayonnaise, £1.49 Calories: 354 Salt: 1.8g Fat: 13g Sandwich weight: 181g Weight of prawns: 61g Prawns as a percentage of the sandwich: 33.7 per cent Number of

whole prawns: 24 CONSIdERING this is the cheapest — by some margin — this really isn’t too bad. you get a good mouthful of sweet prawns, though the mayonnaise is possibly too thick.

On inspecting the filling, you see that there are not that many whole prawns — most of the small Atlantic prawns inside have been chopped up.

SO STINGY

SAINSBURY’S On The Go prawn mayonnaise on oatmeal, £2.25 Calories: 357 Salt: 2.44g Fat: 15.3g Sandwich weight: 162g Weight of prawns: 53g Prawns as a percentage of the sandwich: 32.7 per cent

Number of whole prawns: 19 THIS is simply not a good sandwich. There are hardly any whole prawns in the filling, much of which consists of bits of chopped-up crustaceans — some are almost shredded. In fact, despite the very high salt content (2.44g, nearly 41 per cent of an adult’s daily recommended allowance), the sandwich is surprisingly tasteless.

SAUCED UP

BOOTS prawn cocktail (no mayo), £2.40 Calories: 361 Salt: 1.62g Fat: 14g Sandwich weight: 169g Weight of prawns: 32g Prawns as a percentage of the sandwich: 18.9 per cent

Number of whole prawns: 21 A RARE example of a prawn sarnie with not just lettuce in the filling, but tomato, too.

Curiously, it claims to be a no-mayo sandwich, but it has a heavily flavoured ‘cocktail sauce’ which contains egg yolk, mustard, tomato paste and vinegar among other ingredients.

All of that salad means that there aren’t that many prawns squeezed in.

If you want a lower- calorie sandwich (with less taste), you can opt for a Boots Shapers prawn sarnie with 288 calories.

SEASON PRO

WAITROSE Good To Go prawn mayo, £2.40 Calories: 397 Salt: 1.96g Fat: 19.4g Sandwich weight: 157g Weight of prawns: 51.5g Prawns as a percentage of the sandwich: 32.8 per cent

Number of whole prawns: 28 THIS is a good prawn sarnie. It definitely tastes of prawns and, as warned on the packaging, contained a fragment of shell — but at least this is proof that the filling had once been near the North Atlantic.

The mayonnaise is possibly a bit generously seasoned, with a heavy hand on the pepper mill.

Containing 19.4g of fat, it is the most fatty of all the sandwiches after the M&S one.

Maybe, though, this is why it tastes so good.

TOO TINY

ASDA prawn mayonnaise, £2 Calories: 369 Salt: 1.8g Fat: 12g Sandwich weight: 182g Weight of prawns: 56.5g Prawns as a percentage of the sandwich: 31 per cent Number of whole prawns:

34 THIS has lots of whole prawns but they were pretty tiddly, so make up less than a third of the weight. Less generous, therefore. Good balance between prawns and mayo, but the bread was cardboardy.

GO CRAY-ZY!

PRET A MANGER crayfish and avocado, £3.99 Calories: 383 Salt: 1.4g Fat: 14.6g Sandwich weight: 221g Weight of fish: 50g Hyped: The new M&S Our Best Ever prawn sandwich, left Crayfish as a percentage of the sandwich: 22.6 per cent

Number of whole crayfish: 27 PRET’S twist on the classic prawn sandwich uses crayfish from the freshwater lakes of the yangtze River and adding avocado and salad.

The result is a big mush, with the crayfish fighting amid the mix of avocado, yoghurt mayo, salad leaves and large bits of black pepper.

Pret makes some great products, but this isn’t one of them, especially considering the high price.

BIG HITTER

TESCO prawn mayonnaise on malted brown bread, £2.20 Calories: 383 Salt: 2.1g Fat: 14.7g Sandwich weight: 172g Weight of prawns: 59.5g Prawns as a percentage of the sandwich: 34.6 per cent

Number of whole prawns: 44 TESCO gives M&S a very close run for its money. It has more prawns, but they are small and not full of flavour. They’re clumped in the middle, so you get a huge mouthful if you take a bite out of the centre, but none near the crusts. At 34.6 per cent, its prawn-to-sarnie ratio is only fractionally behind M&S.

ALL FULL UP

MORRISONS prawn mayo on oatmeal bread, £2 Calories: 396 Salt: 2.16g Fat: 15.9g Sandwich weight: 179g Weight of prawns: 48g Prawns as a percentage of the sandwich: 26.8 per cent

Number of whole prawns: 24 ANOTHER sarnie which suffers from having lots of cut-up bits of prawn. The filling isn’t bad, with a good hit of seafood which manages to shout above the rather buttery mayonnaise. The bread, however, is pale and tasteless.

SPICY KICK

M&S Our Best Ever prawn sandwich, £3.60 Calories: 533 Salt: 3.2g Fat: 28.6g Sandwich weight: 245g Weight of prawns: 85g Prawns as a percentage of the sandwich: 34.7 per cent

Number of whole prawns: 30 INdULGENT in every sense. As the hype promises, it has more prawn filling (as a percentage) than any rival. But Tesco is close behind. It also has the most calories, and is the saltiest, with more than half an adult’s RdI.

Are those calories worth it? Well, if you like a classic prawn cocktail, this is the sarnie for you. It has a spicy kick and the prawns are the plumpest and juiciest.

It may justify M&S’s boastful claims — but frankly, I never want to see another prawn sarnie in my life.