How will the royal baby grow up?

AS part of one of the most famous, privileged families in the world, what will childhood be like for the Duke and Duchess of Cambridge's son?

The youngster will grow up, just as William did, with the knowledge that he will one day be king.

But with three generations of monarchs - the Queen, the Prince of Wales and William - between the baby and the crown, the prospect of ruling as sovereign looks likely to be a long way off.

A private education beckons, as well as an elite nursery and possibly a stint at boarding school. William went to Eton.

William calls his father "papa" and called his mother "mummy".

He also had childhood nannies - Olga Powell and Tiggy Legge-Bourke - to whom he was very close.

It is thought unlikely that the Duke and Duchess will employ a full-time nanny, but it is expected they will either opt for a part-time nanny to enable them to carry out official duties or turn to Kate's mother Carole Middleton instead.

William and Kate will do their utmost to give their child as normal an upbringing as possible as they grow up in the world of the Windsors.

The Duke has often spoken of how important it was for him to be treated like everyone else.

He relished the time he spent away from the media at university, where he met and fell in love with the Duchess, and in the armed forces.

Kate too, although also from a wealthy background, has been praised for her down-to-earth approach.

The child's milestones - from their first day at school to their first public engagement - may well be recorded by the media and a barrage of photographers just like William experienced.

Yet this could be kept private to offer as much protection to their child as possible.

The baby's central London home will be Kensington Palace's Apartment 1A, which used to belong to Princess Margaret.

With a big, private walled garden, there is plenty of space to play outside, as well as scores of rooms to explore.

It is being refurbished at a cost of STG1 million ($A1.67 million) to the taxpayer so far, with STG600,000 spent on internal refurbishments including removal of asbestos and STG400,000 spent on repairing and renewing the apartment's roof.

The cost of decorating the rooms, which is expected to be substantial, is being met privately.

William and Kate are also expected to use the 10-bedroom Georgian Grade II-listed house Anmer Hall on the Queen's Sandringham estate in Norfolk as their country retreat.

The family already has its first pet - a black cocker spaniel called Lupo.

The baby will also have to get used to the Queen's beloved corgis and dorgis - a cross between a corgis and a dachshund.

Summer holidays will often be spent with the family in the Scottish countryside up at Balmoral - only for this youngster, grandpa will also be the Prince of Wales and great-granny the Queen.

Royal children greet the Queen with a kiss on both cheeks and a bow or a curtsey.

Christmases will partly be at Sandringham in Norfolk with the royals or with the Middletons in Berkshire and trips to Buckingham Palace and Windsor Castle will expose the youngster to opulent surroundings.

Prince Harry will also be a doting uncle while the Middletons too will play an important part in the baby's life, with the Duchess particularly close to her family - her mother, father Michael, sister Pippa and brother James.

When the Queen was a child, she was heir apparent by the time she was 10 and Charles was heir to the throne when he was just three.

But for this baby, born third in line, the responsibility of wearing the crown is a distant future event.

At some stage, though, the royal baby can expect to be prepared for their important future role - possibly lessons on the constitution or simply by watching relatives at work.

William and Kate's child may also accompany them on official trips overseas.

Royal protection officers will always be close by, while help from housekeepers and aides will be the norm.

Church services will also be familiar - this baby will one day be Supreme Governor of the Church of England.

The baby is also likely to experience a stint in the armed forces, particularly as a future head of the military.