Arthur

A middle name of the Prince of Wales, Arthur is also one of Prince William's middle names as well as the Queen's father, George VI.

The legendary King Arthur was the mythical leader of the knights of the Round Table, who supposedly lived in the 5th or 6th century.

Once popular, the name fell out of fashion, but has had a revival in recent years. Former prime minister David Cameron has a son called Arthur.

Albert

Queen Victoria used to insist that the name Albert was used as a middle name by her descendants, if not a first, in honour of her much-loved consort Prince Albert.

By choosing Albert or Bertie for a boy, the Duke and Duchess would be honouring Queen Elizabeth II's father, George VI, who was actually Albert Frederick Arthur George but always known to his family as Bertie.

Shy, stammering Bertie was forced to become king when his brother Edward VIII abdicated, but won the nation's affection by standing firm in London during the Second World War.

Philip

A lasting tribute to the Duke of Edinburgh might see the new Prince of Cambridge called Philip.

Both Prince Charles and Prince William have Philip as a middle name.

The Duke of Edinburgh - known for his dedication to duty and his acerbic wit - has been married to the Queen for more than 70 years and is the nation's longest serving consort.

Frederick

A Prince Freddie of Cambridge would have a historical link to the 1st Duke of Cambridge.

Prince Adolphus Frederick lived from 1774 to 1850 and was a son of George III.

He was apparently very fond of interrupting church services by bellowing out "By all means" if the priest said "Let us pray".

Charles

William may want to pay tribute to his father - but perhaps as a middle name as it may be considered too similar to Charlotte.

James

James could be chosen to signify the Duchess's affection for her brother, the baby's uncle, James Middleton.

William already has a cousin James, the Earl and Countess of Wessex's son, Viscount Severn.

James is a Stuart name. James I, son of Mary, Queen of Scots, had been king of Scotland for 36 years as James VI when he became king of England in 1603.

Other names

They could choose William as a middle name for a boy, but also perhaps Michael as a middle name out of respect for Kate's father.

Kate's grandfather on her paternal side was called Peter, while on her maternal side, her grandfather was Ronald.

Thomas also appears several times in Kate's family tree, as does Francis.