Talking of English girls marrying into the Royal family, as I did in this column last week, a reader has pointed out that one such was Joan of Kent, who married Edward of Woodstock, otherwise known as the Black Prince, born at the Royal Palace of Woodstock in 1330.

True enough. Then there was Isabel of Gloucester. She married the future King John, born 1167 at Beaumont Palace, Oxford, which once stood at the bottom end of what is now Beaumont Street, opposite the present Worcester College.

But it is extraordinary how few such girls went on to become queens. Isabel’s marriage, for instance, was declared void in 1199, the year John became king, on the grounds of consanguinity — since her grandfather was the illegitimate son of Henry I, and the two were, therefore, second cousins.

A descendant of John, the beautiful Elizabeth Woodville, daughter of Earl Rivers, was the first commoner to marry an English king. Her marriage to Edward IV took place in secret in Northamptonshire in 1464, and caused some red faces among powerful courtiers who had been negotiating a marriage to a French princess.

But by the 19th century, and in the light of the Royal Marriages Act of 1772, secret marriages to possible heirs to the throne had become tricky because the Act required (and requires still) that the sovereign’s permission be given for any marriage into the Royal family.

One such person who was, therefore, forced to live happily with his mistress and their ten children for some 20 years was the Duke of Clarence, the future “Sailor King”, William IV (above). He lived at Bushey in Middlesex with Dora Jordan, a popular actress on the Drury Lane stage.

One of their children, Lord Augustus FitzClarence, became vicar of the Oxfordshire parish of Mapledurham from 1829-1854. The reverend son of the King of England lived in the modest stuccoed vicarage with its three bay windows near the church, and here at the age of 40 he brought his 16-year-old bride, Lady Sarah Gordon.

His father in time married a German princess — later Queen Adelaide — when it became apparent that, though only a third son of George III, he was nevertheless likely to succeed to the throne of Great Britain and Hanover.

But he never forgot his Dora. On becoming king, at the age of 64, he commissioned the fashionable and expensive sculptor Sir Francis Chantrey — who had sculpted likenesses of George IV, the Duke of Wellington, and Nelson — to carve a huge monument to her. A life-size statue was duly commissioned at a cost of £2,000.

The king had intended the statue, which also portrayed two of the children of Dora and William, to be placed in Westminster Abbey; but the Dean of Westminster, scandalised, refused to accept it. The Rev Lord Augustus FitzClarence therefore had it shipped by boat down the Thames, to Mapledurham — where it remained more or less unnoticed for some 60 years.

Then, in the early 20th century, long after the son of its subject had himself been buried in the churchyard outside, another member of the family claimed it back.

He was the Earl of Munster, descendant of the elder son of Dora, whom William had ennobled. In 1980, the fifth Lord Munster presented the statue as a gift to the Queen. It now stands in Buckingham Palace alongside statues of Royal personages who would not have welcomed Dora into their homes during her life.

The tale does not quite end there though. The sculptor Chantrey had made a cast of the statue before setting it in stone. This cast was left by his widow to the Ashmolean Museum, Oxford, where it was stored in the basement. Sadly, when the Second World War broke out the museum decided that the cellars might be needed as air raid shelters and they set about a macabre operation to make room: casts were smashed; but some, including the statue of Dora, were selected to have their heads sawn off.

So now the museum possesses a cast of the head of the king’s mistress, but not her body.