Royal Family Photo Album: Prince William, Kate Middleton and Children

Royal baby watch has officially begun in Britain. The installation of crowd control barriers outside the London hospital where both of Prince William and Kate Middleton's children were born suggests the birth of their third child is imminent.

Royalists and the world's media are expected to begin gathering outside the Lindo Wing of St Mary's Hospital in the hope they might catch a glimpse of the baby, even though Kensington Palace hasn't revealed the actual due date.

Another thing that is being kept under wraps is the baby's gender, but whether it's a boy or a girl, the new arrival will be fifth in line to the throne, behind Prince Charles, Prince William, Prince George and Princess Charlotte.

Now aged four and two respectively, George and Charlotte have grown up in the public eye. In this Newsweek gallery, we look back at some of the most charming photos of the young royals.

Above: Kate and William are pictured leaving The Lindo Wing with their newborn son, Prince George, on July 23, 2013.

The next month or so is a busy time for the royal family: William's younger brother Prince Harry is marrying his fiancée, former "Suits" actress Meghan Markle, on May 19.