THEY were taken into battle by the British armies of the First World War and carried by explorers probing the frozen North Pole.

But now fans of the McVities Digestive biscuits, which began life in an Edinburgh bakery, will have to make do with less after the company announced it is shrinking the size of packets of the snack.

McVities owner Pladis UK has said that the weak sterling in the wake of Brexit has driven up the cost of ingredients and the company will now be switching from 500g packets to 400g in a bid to save money.

Many have complained that the decision takes the biscuit – or seven to be exact, as packs will be down by this many Digestives when the plan comes into force.

The news was greeted with dismay by biscuit-lovers, who were angered to see one of the quintessentially British products being thinned down and took to social media to show their displeasure.

Suzanne Evans tweeted: “What utter tosh. Will McVities put seven more biscuits in the pack when the pound rises again? Of course they won’t,” while Dave Shaw wrote: “Can someone please explain why there is some sort of attack on food at the moment? First it was the change in Irn-Bru and now McVities are having a go. What is is this?”.

Others saw the shrinking packets as sign of wider problems with the Government’s strategy, as businesses make plans to deal with the fall out of the decision to leave the Single Market.

Francis Grove-White, deputy director of the Open Britain campaign, said: “No wonder the latest polling shows support for hard Brexit is crumbling.

“The everyday consequences of the post-Brexit fall on the value of the pound are difficult to digest.

“The Brextremists are taking the biscuit with their support for a recipe of leaving the Single Market and the Customs Union.”

McVities was established by baker Robert McVitie and his father William in Rose Street, Edinburgh, and grew to be a national success across the UK with factories in London, Manchester and Glasgow.

The Digestive was invented in 1892 by baker Alexander Grant, who rose from humble origins to the top of the company and was eventually named Baronet of Forres, his home town, by Prime Minister Ramsay MacDonald.

The biscuits, which turned 125 two years ago, have proven enduring popular with the British public to this day, with annual sales of £135 million.

McVities introduced a chocolate-coated version of the Digestive in 1925, although it is a little-known fact that the chocolate is on the bottom of the biscuit, not the top.

The company, which also produces Rich Tea, Hobnobs and Penguin biscuits, was bought by Turkish venture capitalists Yildiz in 2014 and became part of the company Pladis.

Nick Bunker, managing director for Pladis UK & Ireland, said that changes to the market have had a significant impact on their manufacturing process.

“The rising cost of ingredients and changes in the exchange rates means it has become more expensive to bake our products,” he said.

“We work hard to drive efficiencies throughout our business to absorb cost increases, but occasionally, like many other businesses in these challenging times, we do need to make some adjustments.”

McVitie’s Digestives sparked a previous consumer backlash following changes to the recipe in 2009 which were reversed a few years later.

The McVitie’s Digestive biscuit recipe was altered in two stages, removing palm oil and replacing it with the reduced saturated fat sunflower oil.

However, the move was unpopular and the traditional method of cooking was restored in 2014.

“We’re proud to bake the nation’s favourite biscuits, and we have a responsibility to keep baking the same great tasting snacks that people know and love, using the best ingredients, while safeguarding the affordability of our brands which are sold at everyday prices,” Mr Bunker said. “So, after listening to thousands of our consumers, we have taken the decision to review the pack and promotion strategy.”