Can you believe itâ€™s been 3 years?

Wedding day ... Prince William of Wales kisses his wife Kate, Duchess of Cambridge on the balcony of Buckingham Palace in London on April 29, 2011. Source: AFP

FRESH from their 19-day tour of Australia and New Zealand, the Duke and Duchess of Cambridge are celebrating their third wedding anniversary.

They arrived at London's Heathrow Airport on Saturday after the long flight back from Australia with Prince George, whose first royal trip saw him become the star of the show.

After three weeks away, it is more than likely the couple will soon be catching up with the Middletons and the rest of their extended family to reunite them with baby George and show them how much he has grown.

The nine-month old acquired an "extra fat roll" during the trip, according to Kate, as well as a fuller head of hair.

The Cambridges, who wed at a glittering Westminster Abbey ceremony on April 29, 2011, watched by a worldwide audience of millions, have had a whirlwind 12 months.

The world was watching ... Britain's Prince William and his wife Catherine, Duchess of Cambridge, on their wedding day. Source: News Limited

They became parents for the first time in July and moved into their renovated Kensington Palace apartment in the autumn, while William left his job in the military and took an agricultural management course at Cambridge University.

Their successful trip to New Zealand and Australia — which included a playdate for George in Wellington, a visit to Uluru at sunset, meeting lifesavers on Manly Beach in Sydney and paying tribute to fallen soldiers on Anzac Day — was one of the longest, high profile overseas royal tours for many years.

Traditionally couples exchange gifts made of leather to mark their third wedding anniversary.

But Kate has acquired several new pieces of jewellery in recent months. Both her 3600-pound ($6557) Ballon Bleu de Cartier watch, which is embedded with a sapphire to match her engagement ring, and a diamond eternity band, which she wears on her wedding finger, are thought to have been gifts from William.

New Life ... Since their wedding three years ago, William and Kate have welcomed Prince George into their lives. Source: Getty Images