Clay from Cornwall in King Charles' coronation commemorative china

Cornwall’s china clay industry is famous around the world, and at one point, in the early 20th century, it was producing 50 per cent of the materials used in the production of porcelain.

Indeed, the English porcelain industry began thanks to the discovery of kaolinite – the essential component in china clay - at Tregonning Hill near Germoe in west Cornwall, in 1745.

However, it is St Austell that is most associated with its production, and the manmade ‘mountain’ created is often dubbed the ‘Cornish Alps’.

By the early 19th century, Cornwall was found to have the largest deposits of china clay in the world.

Its use in the royal china is perhaps particularly fitting given the King’s role as Duke of Cornwall over so many decades.

It is being used alongside similar clay from Devon to produce the official chinaware marking the ceremony on May 6, which will take place at Westminster Abbey in London.

Some of the commemorative mugs before they are fired (Image: Richard Vernalls/PA)

According to the PA news agency the range, made in The Potteries in Stoke-on-Trent, features a bespoke design incorporating the royal coat of arms and a garland of laurel leaves symbolising peace.

Also featured is a decorative border of oak leaves signifying strength and longevity alongside the emblems of the four nations of the UK – the thistle, rose, shamrock and daffodil – while an entwined ribbon symbolises the partnership of King and Queen Consort.

The design features Charles’s cypher, which is stamped in gold foil, designed by The College of Arms and consists of initials from his name and title, rex, which is Latin for king.

Behind it is the Royal Collection Trust charity, part of the royal household, which has been making commemorative china for 30 years.

Ian Grant, the trust’s head of product development and buying, said it was “probably the most momentous occasion we’ve developed a product for.”

The King’s cypher, shown here printed on one of the souvenir item’s boxes (Image: Richard Vernalls/PA)

On the factory floor in Stoke, the high quality white clay Cornwall and Devon is machine-mixed with water and other ingredients to form liquid clay, known as slip, which is sieved for impurities and then piped and hand-poured into moulds by staff using pressurised hoses.

The drying clay pieces must then be removed at precisely the right moment, in a process requiring careful timing, from the plaster of Paris moulds.

More slip is used like a glue to attach individually moulded handles, if needed, by hand.

Before firing in a kiln, the dried clay goes through wet-sponging and fettling – where the seams from the casts are carefully removed by hand in a process which has gone unchanged for decades.

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The coronation range is made up of a coffee mug priced at £30, pillbox at £40, tankard at £50, an eight-inch dessert plate also at £50, and a tea cup and saucer at £75.

There are also several limited edition lines that will be hand-numbered, produced in smaller runs ranging from 150 up to 1,000 and be “a little bit more special”, Mr Grant said.

Profits go to the trust for the care and conservation of the Royal Collection.