Royal expert BRIAN HOEY on the history behind the royals' love of kilts and tartan - as King Charles continues his stay at Balmoral

His Majesty has been at Balmoral with Queen Camilla since August, and is set to stay there until October.

In spending the summer and autumn at the castle that was so much loved by his mother, King Charles is demonstrating his deep affinity with Scotland.

Fittingly, the monarch arrived at Balmoral wearing a tartan kilt, although his chosen pattern on August 19 was not Royal Stewart.

That pattern is the personal tartan of the monarch and officially no one can wear it without his permission.

But that exclusion is mainly ignored these days – for commercial reasons.

The companies who sell the tartan and kilts know there is a market throughout the world, so they encourage the sale wherever they can.

And people will always buy it, believing they are achieving a connection with royalty.

You can even buy boxes of shortbread bearing the royal tartan emblem.

There is no record of anyone being prosecuted for wearing the tartan.

I have experienced just a single occasion when the wearing of a kilt with Royal Stewart tartan was punished.

I was talking to a member of the Household at Balmoral when he told me about one of his predecessors.

He said: 'He suddenly appeared one evening in the downstairs sitting room wearing a kilt with the Royal Stewart tartan and curtseyed to the head butler, who wasn't amused.

'The next morning he disappeared from Balmoral – and the Household, and has never been seen again, And never will be!'

Although the history of wearing a kilt goes back centuries and relates to the clan system in Scotland, the Royal Family adopted it only in 1830.

But since then, every year as Summer approaches, the King and his family goes 'native'– no offence to the People of Scotland intended.

In the 19th century it was Queen Victoria (who else) who first adopted the tartan and kilt.

With Victoria, her word was sacred and every syllable had to be obeyed immediately and without question.

Her husband Prince Albert is said to have designed so-called Balmoral tartan, which is distinct from Royal Stewart tartan.

The Balmoral pattern is said to have been based on Royal Stewart and was first manufactured in the 1850s.

All of Victoria's successors, with a few reluctant exceptions, have worn kilts. The late Queen Elizabeth's father, King George VI, didn't like them but for his older brother King Edward VIII, later Duke of Windsor, the dislike was a positive hatred.

He refused to wear one on any occasion, even the Highland Games, saying they made him look like a pantomime dame.

Perhaps it was because he simply did not have the legs to support a kilt.

Of course, King Charles has never known what it's like not to wear a kilt in Scotland. He grew up being used to it and he claims he loves them.

Queen Elizabeth wore tartan plaid throughout her stay at Balmoral and, as far as anyone knows for sure, it was one of her favourite patterns.

Of the present generation, Prince William is believed to be hesitant about wearing a kilt - although was spotted in one when he was a young boy.

Prince Harry, the Duke of Sussex, is pretty easy-going about such things, but again, a picture of him in a kilt would be a worldwide hit.

Royal Stewart is worn by military pipers of the Black Watch, Royal Scots Dragoon Guards and the Scots Guards.

And certain privileged civilian groups, mainly in Canada, with one in Australia, are also permitted to wear it as part of their official uniforms.

When kilts first came to be used it was as a form of clan identity. But not, as many people believe, on the bodies of men killed in clan battles.

The tartan kilt was worn before a battle started and then it was discarded and a plain, tougher leather kilt was put on, to provide more protection against weapons.

They were also all worn just below the knee, as protection from the heather as well as the enemy, who happened to be another clan.

However, there is one rule that govern the wearing of the kilt that all true Scotsman follow.

True Scots should not wear any form of underwear under their kilt. Nobody knows if the Royals obey the rule by 'going commando'.

But nothing will ever change the attitude of the Royal Family towards Balmoral, or towards kilts and Royal Stewart tartan.

The love of all three is a tradition engrained in the very souls of the royals. And it won't change any time soon.