There are few people who at 71 years of age would contemplate taking on one of the most stressful child care jobs in the world – looking after Prince George.

So it is perhaps no surprise that Jessie Webb, who looked after Prince William when he was a child and came out of retirement to mind baby George, has told William and Kate that she will not be able to accompany them on their month-long tour of Australia and New Zealand in March.

While William and Kate are said to be keen to retain the services fo Mrs Webb, they are quielty looking for extra help for the month-long tour down under in the spring.

A source told the Daily Mail: "It took a lot of persuading to get Jessie to take the job in the first place, but she loves William and wanted to help out.

"I can't imagine that she will want to be travelling around the world at her age.

"If she does, she will need an assistant."

The Duke and Duchess will spend a month criss-crossing Australia and New Zealand.

Another source told the paper: "They need round-the-clock help for George if he joins them. Kate might also want to think about taking a dresser or a lady's maid. It sounds grand, but it's actually very practical. The Queen wouldn't dream of travelling overseas without a lady-in-waiting."

Rumors that Carole Middleton would join the Australian tour to help look after Prince George have been scotched by the palace.