Queen 90th birthday
The Queen poses with her son, grandson and great-grandson in the White Drawing Room at Buckingham PalaceRoyal Mail

Queen Elizabeth II may be celebrating her 90th birthday but her great-grandson Prince George is hogging the spotlight. The toddler appears on a new royal stamp to celebrate the Queen's milestone birthday and completely commands the attention away from his father Prince William and grandfather Prince Charles, who also appear in the portrait.

In his first ever appearance on an official royal stamp, two-year-old Prince George stands on a set of foam blocks wearing a wide smile and holding onto Prince William's hand. The Queen sits proudly on a gold sofa with her eldest child and next in line to throne Prince Charles positioned beside her. The family photo was taken by photographer Ranald Mackechnie in the White Drawing Room of Buckingham Palace in the summer of 2015 and will feature as part of a 10-part stamp special to commemorate the Queen's 90th.

The portrait is part of a stamp sheet with perforations so the images of Queen, Prince Charles, Prince William and Prince George can be used individually. Other stamps from the unique collection include the Queen with late South African president Nelson Mandela, posing with Prince Charles and Princess Anne as children and HRH with her father King George VI. The stamps will be made available to buy from Post Offices from 21 April 2016, which is the Queen's actual birthday, but can also be pre-ordered from Royal Mail on 20 April.

Queen 90th birthday
A set of stamps released to celebrate the Queen's 90th birthdayRoyal Mail

Speaking about the honour of taking the rare family portrait, Mackechnie said: "It's great just to be asked to photograph a stamp, never mind four generations of the royal family. When I was asked about it I was ecstatic but I had to keep schtum for 18 months. It was an amazingly relaxing and light-hearted sitting. They were comfortable with one another and behaved like any family with their conversation and jokes.

Queen 90th birthday
Stamps featuring four generations of the House of Windsor, photographed for Royal Mail by Ranald MackechnieRoyal Mail

"It was much more relaxed than when I've tried to take pictures with my family. The joy and energy coming out of George was fantastic. It lifted the whole shot and lifted the afternoon. He was on top form. He was quite fascinated by the lights. He took it all in his stride." Prince George has appeared in several family portraits, most notably an image from a skiing holiday with his mother Kate Middleton, the Duchess Of Cambridge, Prince William and 11-month-old sister Princess Charlotte.

Coincidentally, the Queen will be visiting a Royal Mail delivery office in Windsor on 20 April beginning her 90th birthday celebrations.

Incredible archive video charts life of Queen Elizabeth IIIBTimes UK