Prince Edward has been made Earl of Wessex and Viscount Severn in honour of his marriage to Sophie Rhys-Jones.

Sophie will now be styled Her Royal Highness, the Countess of Wessex, shortened to simply Sophie Wessex.

It has also been agreed that Edward will also become Duke of Edinburgh after the death of his mother, the Queen, and his father, Prince Philip, who currently holds the dukedom.

It is believed to be in recognition of his work with the Duke of Edinburgh award scheme.

In a modernising touch, the couple's children will not be given the style His or Her Royal Highness, "but would have courtesy titles as sons or daughters of an earl".

The decision reflects "the clear personal wish of Prince Edward and Miss Rhys-Jones as being appropriate to the likely future circumstances of their children," said a spokeswoman before Saturday's wedding.

But some constitutional experts say that Edward has been slighted, because he should have received a dukedom.

Edward will be Duke of Edinburgh when his parents die

The title of earl is more usually conferred on commoners who marry into the royal family. Both of Edward's brothers were made dukes when they married.

Harold Brooks-Baker, publishing director of Burke's Peerage, said the decision to make Prince Edward an earl rather than a duke indicated that he would play a minor role in public life.

"He is the first son of a monarch in this dynasty going back to George I not to be made a duke. He has been promised the title of Duke of Edinburgh but we don't know if there will be a monarchy in the future.

"For his children not to be styled prince and princess is a huge departure as well."

Wessex made famous by Hardy

The title Earl of Wessex has not been used since the 11th Century, when the last earl, King Harold II, was famously killed by an arrow through the eye during the Battle of Hastings in 1066.

Wessex: Not used since the Battle of Hastings

The tribal kingdom of Wessex was established in the 6th Century and grew to include most of southern England by the time of King Alfred.

The term Wessex died out but was revived in the 19th century by the Dorset poet William Barnes and made famous by author Thomas Hardy.

The general consensus is that Wessex covers Dorset and Hampshire but also includes parts of Wiltshire, Berkshire and even Devon and Somerset.

Historian Dr David Starkey said: "The title itself is a total fiction. There is nowhere called Wessex...the title has not been used for a thousand years - is it the right way to celebrate the third millennium by going back to the first?"

The title Viscount Severn is derived from the Welsh roots of Miss Rhys-Jones's family.

Mr Brooks-Baker said the title was "of little significance".

"Viscount Severn was used by minor members of the royal family years ago. It is an 18th Century title. There is a history of being given a secondary title so the eldest son can have it is a courtesy title," he said.