The future heir to the throne could also take the crown of tallest royal, as new photos showed Prince George, 12, standing shoulder to shoulder with his mother, the Princess of Wales. The oldest child of Prince William and Catherine is 'growing up so fast,' royal fans said after official pictures from George's recent visit to RAF Coningsby were shared online. One X user shared a side-by-side comparison of William, then 15, standing next to his late mother, Princess Diana, and George at 12 with Catherine during the pair's poignant trip to the RAF base. William's height at the time was 179cm or nearly 5'9", whereas George - who turns 13 next month - is already 175cm or around 5'8". At 6'3, the future King is the tallest member of the British Royal Family, but 'it looks like William's reign won't last much longer,' the X user commented on Prince George's growth spurt. When William's young cousin, the Earl of Wessex, joined the Royal Family for Peter Phillips and Harriet Sperling's wedding in the Cotswolds last month, fans were quick to point out that 18-year-old James towered over his father, Prince Edward. The King's younger brother is believed to be around 6', meaning his 18-year-old son might be between 6'1" and 6'2". In fact, he is likely to be around the same height as Prince Harry, who falls an inch below William.