King Charles is said to use a very old-fashioned and common item when it comes to his bathroom ritual. Last December, the monarch , including Champagne Bollinger, Enterprise Rent-A-Car, Heinz Foods and Molton Brown.

Buckingham Palace said the warrants previously held by Queen Elizabeth have been will continue to hold warrants from the King. One of those businesses was Bronnley, which was awarded a royal warrant for the third time for being a supplier of soaps. The company was founded more than 140 years ago, in 1884, by James Bronnley when he was just 19 years old.

Since then, it has been granted a royal warrant three times - once in 1943 by King George VI, in 1955 by Queen Elizabeth II, and last year by Charles.

Bronnley's most famous product, yellow-coloured, (£8.50), first created in 1892, is said to still be used by the monarch as bar soaps are reportedly having a big comeback into the beauty scene.

The company says on its website: "Discover the timeless quality of a renowned Bronnley classic, one that earned us the title of Best Soapmakers in the World.

"The first of its kind, our fine-milled Lemon Soap was created over 100 years ago, conforming to the original fruit shape, right down to the grainy texture.

"Formulated to delicately cleanse, today the soaps still exude a fresh, citrus scent with vibrant hints of Lemon and Lemongrass, heart notes of Aldehydes and Neroli, and base notes of Cedar, Ambergris and Musk for a grounding finish."

The 's beauty editor Sonia Haria praised the product and said: "It turns out soap bars are in fashion again, after years of plastic-pump hand washes reigning supreme.

"There's something so satisfying about how well a bar of soap lathers up in your hands, plus the newer formulations don't feel skin-stripping - which I've always found very off-putting - and are mostly very moisturising.

"For a product that was originally created in 1892, the Bronnley Lemon Soap has stood the test of time, and it is still produced in the UK in small batches - a rarity nowadays. It's also incredibly popular: one bar of the brand's soap is sold every four minutes."