Grimy oven shelves are a source of frustration for countless households. Stubborn baked-on grease can contaminate food and even trigger smoke alarms the moment you open the oven door.

Yet it's remarkably easy to put the issue out of your mind once you've settled down to your Sunday roast - until the next time you fire up the appliance.

When people do eventually tackle oven cleaning, it's an unpleasant, labour-intensive task that typically involves harsh chemicals. So it would be a welcome relief if there were a simple, natural approach to cleaning oven shelves that required minimal scrubbing.

As it turns out, Great British Bake Off winner Nancy Birtwhistle believes there is indeed a solution. Nancy, who as one of Britain's most accomplished bakers relies on her oven far more than most, swears by a surprisingly effortless technique.

Nancy, who triumphed in the fifth series of The Great British Bake Off in 2014, says she is determined to protect the planet for her 10 grandchildren and avoids harmful chemicals wherever possible when cleaning her home.

She revealed her eco-conscious oven-cleaning trick to Yours Magazine: "At the first signs of baked-on foods on oven shelves, throw them onto the lawn overnight. A quick wipe the next day and they are as clean as a whistle."

Tempting as Nancy's approach may sound, not every expert is convinced it's the definitive solution. Petya Holevich, a house cleaning expert from oven cleaning specialists Fantastic Services, cautions that simply leaving the shelves on the grass overnight may not always suffice on its own.

"While the idea of using grass to clean oven racks sounds interesting to many people as an alternative natural cleaning method to avoid using harsh chemicals, it isn't necessarily the most effective one," she told Ideal Home Magazine.

Petya explained: "While grass has some abrasive properties that can help loosen dirt and food residue from the oven racks, it isn't specifically something designed for cleaning and there's no actual guarantee that it will effectively remove more stubborn grime and grease."

Domestic and General's appliance repair expert Ian Palmer-Smith suggests that Nancy's oven solution might prove a decent starting point but is unlikely to suffice on its own: "The moisture in the grass may help remove some debris from the oven racks, but you're unlikely to notice any significant improvements," he says.

Rather than leaving your oven shelves gleaming, exposing them to the elements could potentially worsen the situation, according to AO's oven expert, Isabella Forgione.

Despite this, she maintains that's no justification for resorting to the harsh chemicals present in costly oven-cleaning products, instead recommending natural alternatives such as lemon juice and white vinegar: "We always suggest making a natural oven cleaner from simple items found in your kitchen cupboards, rather than buying expensive cleaning products for different parts of your home."

Isabella advises: "To create a natural and effective cleaning solution, mix baking soda and white vinegar to create a paste. Apply it to the oven racks and leave it to sit overnight. Then, dip a cloth in hot water and wipe away any remaining residue to leave your oven sparkling clean."

Stubborn grease and grime will dissolve effortlessly when doused with pure lemon juice, Isabella explains: "Simply apply lemon juice directly to the oven racks, let it sit for a few hours, then scrub and rinse."