Princess Diana
If they have a daughter Kate and William plan to name the baby after Princess DianaGemma Levine

Royal biographer Andrew Morton has added to speculation that the Duke and Duchess of Cambridge will name their second child Diana, if it's a girl.

Morton, who wrote a biography of the Princess of Wales, Diana: Her True Story in 1992, which exposed the truth of her strained marriage, said a daughter would be given the name Elizabeth Diana Windsor.

He told The Sun on Sunday: "Close friends to William and Kate have told me that if it is a girl they want to name the baby after Diana. They discussed girls' names before George was born and now they're hoping the next one is a girl so they can carry out their wish to honour William's mother. They're not too thrilled at the thought it will be shortened to Princess Di. But it won't change their minds."

The decision could of course ruffle some feathers in the royal household, in view of the 'hostility' that existed between Diana and senior members of the royal family, but Kate and William are said to be determined to honour the memory of the late princess.

Following Morton's claims, bookies reported that punters are putting £1000 on the name. Elizabeth became 10/1 favourite for the name with Coral bookmakers. James is second at 11/1, Victoria third at 12/1 and Alexandra fourth at 14/1.

In November 2010, William famously gave Kate the engagement ring that once belonged to Diana, saying it was 'my way of making sure my mother didn't miss out on today and the excitement'.

The latest royal pregnancy was announced on September 8, as it was revealed that Kate was suffering from acute morning sickness and being treated by doctors at Kensington Palace.

The new baby will be delivered at St Mary's Hospital in Paddington, central London, where Prince George was born in July 2013.

The couple will then set up home in Norfolk.