As the nation prepares itself for a fresh bout of Great British Bake Off fever, Prue Leith, one of the faces of the revamped show that hits TV screens on Tuesday, is putting her support behind a campaign to protect the provenance of artisan bread.

The push for an “Honest Crust act” by the Real Bread Campaign is designed to ensure that not only do consumers know exactly what is in their loaves, but also that a level playing field for large supermarket chains and smaller bakeries is created. These include a new generation of microbakeries, which have sprung up partly as a result of the nation’s growing obsession with baking.

“Of course we should know what’s in the bread we eat. The Real Bread Campaign’s call for better labelling legislation will also help small, local bakeries thrive,” said Leith, who is replacing Mary Berry as one of the two judges on Bake Off.

Microbakers and other small independent bakers are increasingly feeling the squeeze from supermarkets selling sourdough and other breads under an an “artisanal” banner. They will be encouraged to make their views known to the government in an online campaign, which gets under way next month. Organisers hope the movement will gain momentum as a result of a new wave of Bake Off fever expected to grip the country soon after the latest series begins on its new home on Channel 4. The campaign – part of Sustain: the alliance for better food and farming – argues that British consumers are prevented from getting honest and accurate information about the loaves they buy because retailers are not required to display a full list of ingredients or declare any artificial additives used in the production of unwrapped loaves. The campaigners also point to an absence of legal definitions for many terms commonly used in loaf marketing, including freshly baked, sourdough, wholegrain, bakery, artisan and craft. A letter, which independent bakers will be encouraged to sign up to will be sent to the environment secretary, Michael Gove, whose department has responsibility for food.

It states: “Microbakeries and other small, local, independent real bread bakeries help to keep our high streets alive, supporting more jobs per loaf and keeping more money circulating locally. However, an update of British loaf labelling and marketing legislation is urgently needed to help protect smaller and craft bakeries from the worrying increase in ‘hijack marketing’ and to ensure that British quality food, and its traditional recipes, local production and standards, can survive and thrive.”

Among the new generation of bakers is Lucie Steel of Hermitage, Berkshire, who runs Birch Cottage Bread. from her home and bakes in a shipping container in the Berkshire countryside. “Bakeries are incredibly difficult to keep going because a loaf of bread is such a small value item,” she said. “Along with your rates, labour and other costs it can be an incredibly expensive business,” she said.

The Real Bread Campaign is urging Gove’s Department for Environment, Food and Rural Affairs (Defra) to introduce safeguarding measures before Brexit amid concern that new trade deals could potentially undermine existing standards. A Defra spokesperson said: “We want consumers to have clear information on food they buy, and we are committed to working with industry to make sure consumers are not misled. When we leave the EU, we will bring the whole body of EU legislation into UK law and will have the opportunity over time to change rules and legislation so they work better for our country.”