When the Queen, then aged 86, was filmed 'jumping out of a plane' during the opening ceremony of the London 2012 Olympics, no one was more surprised than her grandson, Prince William. Describing her as an 'unbelievably good sport', he added:  'Harry got a sniff of a rumour on the night and the rumour mill was going into overdrive. 'But, in fact, she did such a good performance that she's been asked to star in the next Bond film. I'm thrilled for her.' Scroll down for video . Birthday: The Queen, pictured at Newbury Racecourse on Saturday, is celebrating her 89th birthday today . While the Queen's cameo role as a Bond girl came as a surprise to her grandsons, her still-sharp sense of fun did not and, as she turns 89, it's one that shows no sign of diminishing. Just last week, she was spotted looking animated and crossing her fingers at the Newbury Races while cheering on her filly, Ring of Truth. Although the two-year-old bay only managed second place, the Queen, who still goes to the races whenever she can, clearly enjoyed herself. Her Majesty is also a regular rider and is frequently spotted riding out in Windsor Great Park on her black Fell pony Carltonlima Emma - despite, as she turns 89, reaching an age where most other riders have hung up their hats for good. Sense of humour: The Queen proved her sense of humour remains undiminished with her James Bond spoof . Active: The Queen still rides regularly and is pictured out in Windsor Great Park last week . Long-standing love: The Queen, pictured in 1968 and 1972, has long adored all things equestrian . But the Queen is an expert when it comes to defying her advancing years and, along with maintaining a schedule that would leave people a third of her age exhausted, continues to enjoy herself much as she always has. Although recent years have seen her cut down on the amount of time she spends in the saddle - the result of a niggling knee injury that also forced her to give up presiding over Trooping the Colour on horseback - the Queen remains an enthusiastic equestrienne and, according to sources, is a familiar sight at her Windsor stables. She is said to take a keen interest in all her horses and ponies, some of whom are now ridden by her grandchildren, notably Prince Edward's children, Lady Louise and James, Viscount Severn. Her Majesty also puts in regular appearances at the Windsor Horse Show and is frequently seen watching the action during the Cartier Polo Cup - a tournament that takes place at the Guards' Polo Club in Windsor. Although, unlike her grandsons William and Harry, the Queen has never played polo herself, she has long been a fan of the sport. Showing her nerves: The Queen grimaces while watching her filly Ring of Truth last week . Shared love: The Duke of Edinburgh also shares her love of racing and polo . Popular: While the Queen cannot ride as much as she'd like, she still has a heavy work schedule . But while her advancing age has curtailed the Queen's ability to ride, she still partakes in many of the habits picked up as a young woman, among them a penchant for a pre-lunch gin and Dubonnet. Like her mother, who lived to be 102, Her Majesty is also said to be fond of a pre-dinner gin and tonic but turns down fancy fare in favour of plainer dishes. According to former royal chef Darren Brady, a typical lunch for Her Majesty is grilled Dover Sole served with wilted greens - that followed by an afternoon tea with 'at least two kinds of sandwiches' at four. For supper, the Queen has more fish or game such as pheasant sent to Windsor from her estate at Sandringham or Balmoral. Perhaps this hearty but plain fare explains her continuing good health and her ability to manage what remains a heavy workload . Meetings: She meets the British PM once a week and 'regularly speaks' to those elsewhere . Role: The Queen performing her role as Queen of Australia with a visit to an Aboriginal culture show in 2002 . State opening: The Queen, here as Queen of New Zealand, opening Parliament in Wellington in 1977 . Patriotic: The Queen, here of Great Britain and Northern Ireland, meeting children in Hampshire . Her Majesty  spends most afternoons welcoming incoming ambassadors to Buckingham Palace, presiding over investitures or, as she did last week, taking part in visits on behalf of one of the 16 countries of which she is head of state. She also has a weekly audience with the UK prime minister, currently David Cameron, and 'speaks regularly' to the prime ministers of the 15 other countries where she is head of state, among them Australia's Tony Abbott and Canada's Stephen Harper. Under the Queen, the monarchy has also modernised and embraces the latest technology, including social media. The Queen is currently the world's most followed royal, with her account, @BritishMonarchy, followed by 970,000 people. Her first post, an anodyne comment about the opening of an exhibition at the Science Museum, went viral - as did her first photo-bomb. The moment, which came during last summer's Commonwealth Games, saw Her Majesty appear in the background of a selfie being taken by Hockeyroos player, Jayde Taylor, 30. Her Majesty also made her first, if unscheduled, appearance in a selfie in June when 14-year-old Jack Surgenor darted in for a cheeky snap during a walkabout in Belfast's St. George's Market. Photo-bomb! This snap of the Queen by Australian hockey player Jayde Taylor rapidly went viral . First selfie: 14-year-old Jack Surgenor snaps a cheeky selfie with the Queen during a visit in Belfast . First Tweet: The Queen sends her first official Twitter message during a visit to the Science Museum . Beyond selfies and social media, the Queen continues to make waves in the sartorial world with her trademark shift dresses and colourful coats, all of which are regularly referenced by the world's top designers. Even her Launer London handbags are enjoying renewed popularity, with the brand regularly selling out colourful special edition versions of her favourite £1,075 Traviata style. At home, her family are enjoying a period of relative peace and, as she celebrates her 89th birthday, the Queen is about to become a great-grandmother for the fifth time. But for Her Majesty, who is spending today privately with her family at Windsor Castle, the imminent arrival is just one of a number of reasons to be pleased. Still riding, still enjoying the races and still unafraid to surprise family and the public alike, the Queen, nearly ninety, surely is the world's coolest great-grandmother. Happy family: Her Majesty is about to become a great-grandmother for the fifth time . Royal family: The Queen pictured with her family and the Middletons at Prince George's christening in 2013 .
The Queen is celebrating her 89th birthday today at home at Windsor .
She is spending the day privately with Prince Philip and her family .
Her Majesty is enjoying renewed popularity, especially on social media .
A snap of the Queen photo-bombing a hockey player went viral last year .
She is set to welcome her fifth great-grandchild within days .