Mary Berry, Jamie Oliver, Rick Stein and Raymond Blanc are among 50 celebrity chefs and high-profile bakers being asked by free range egg farmers to help end Britain’s obsession with large eggs.

The British Free Range Egg Producers Association (BFREPA) says hens naturally lay a range of sizes and wants more shoppers to try a box of medium or mixed weight eggs rather than large.

The organisation’s chairman, James Baxter, has written to high-profile chefs and bakers to ask them to throw their weight behind the campaign.

In the letter he asks them to publicly support BFREPA’s message that bigger isn’t always better.

He also asks for references to the size of eggs used in recipes to be removed wherever possible.

“We are a nation of food lovers and that is driven on by the fantastic chefs and bakers we have in this country,” Mr Baxter said.

“Free range eggs are a staple of British diets but shoppers have become obsessed with getting the biggest egg they can.

“Egg size can be affected by a number of variables such as the weather, diet and light levels – as farmers bird welfare is our number one priority and we want to allow hens to lay what comes naturally.

“We hope that these letters will resonate with chefs and bakers who are in positions of influence but, more importantly, care deeply about how food is produced.”

Retailer promotions and a perceived sense of added value from consumers continues to drive demand for large eggs, but BFREPA says there is often very little difference between the sizes.

“As the size of an egg increases it contains a greater proportion of white, rather than yolk where the bulk of the nutritional value is contained,” Mr Baxter added.

BFREPA commissioned an explanatory video last year featuring free range egg producer Susie Macmillan of The Mac’s Farm in Sussex which has been watched 100,000 times by consumers.