Prince George will have the world as he knows it turned upside down by his younger sister.

 

As a big brother, the prince will have to learn to share not only his toys but also the affection of his mother and father with the new member of his family.

Just short of his second birthday on July 22, the future king is nearing the "terrible twos" when toddlers unleash their frustration in the form of full-blown tantrums.

Sarah Redshaw, managing editor of BabyCentre.co.uk, said emotions will be running high for the young prince.

"George will be expressing himself, shall we say - all these emotions that they don't know what to do with. There will be tantrums, jealousy will be a thing," she said.

"Toddlers also like exploring. You can't turn your back for five minutes without them wanting to explore the cat litter tray or something like that."

George, according to both the Duke and Duchess of Cambridge, is already a noisy youngster, with Kate remarking he was too loud to take to church on Christmas Day.

In the last 12 months, he went on his first official tour - to New Zealand and Australia - and turned one in July. The hardy royal was also pictured outside in shorts in photos taken in November.

George is now likely to be able to build a tower of six cubes, identify pictures by pointing and have mastered the skill of jumping. He might even be able to say up to 50 words. Potty training may be a little way off unless the prince has shown he is ready to ditch his nappies.

Ms Redshaw suggested George might be potty trained when the baby is around six months old.

"He might be ready for potty training by the time the new baby is starting solids. (Kate) could be starting solids with one and potty training the other which could be a very messy affair," she said.

William and Kate have the help of a full-time, live-in nanny ready to assist them with George as he enters one of the most notoriously tricky ages.

But even this may not save them where tantrums are concerned. One of the best-selling childcare guides, What To Expect: The Toddler Years warns: "A toddler also tends to save up his worst terrible twos behaviour for his parents because his struggle for independence is with them."

William and Kate will have sourced books about being an older brother to read to George and may even have bought a doll to introduce the idea of looking after a baby.

"What some mums do is get a baby doll and get their older child used to having a baby in the house and start talking about nappies and feedings," she said.

"Lots of mums buy a gift from the new baby to the toddler with a message like 'Thanks for being my brother' to make them feel included."