Prince Philip, the husband of Britain\'s Queen Elizabeth II, turns 90 on Friday but will keep the celebrations at a minimum in keeping with the no-nonsense style that has defined a life behind the throne. The gruff patriarch, the longest-serving consort in British history, will spend his birthday at work, hosting a charity reception and chairing a conference for military colonels. Although still sprightly and remarkably fit, the Duke of Edinburgh is bowing to his age and intends to slow his hectic schedule of engagements. But he is as quick as ever when making quips -- some of which have famously landed him in trouble -- and after a lifetime of getting on with it, he showed typical impatience when asked to analyse the past 90 years. He admitted in a BBC interview that he had worked out his role by \"trial and error\", but when asked if he thought he had been successful, he replied: \"I couldn\'t care less. Who cares what I think about it? I mean it\'s ridiculous.\" However, in a sign of the public affection for him, the palace revealed that almost 2,000 birthday cards had been sent to the duke from across the globe, including New Zealand and Australia, Italy, Poland, France and Germany. Prince Philippos of Greece and Denmark, a nephew of Greek king Constantine I, was born on a kitchen table on Corfu on June 10, 1921. After a turbulent childhood, Lieutenant Mountbatten, as he became, married in 1947, but his stellar progress in the British Royal Navy was halted when his wife became queen in 1952 and he was forced to abandon his career. He told ITV it was \"disappointing\", but \"being married to the queen, it seemed to me that my first duty was to serve her in the best way I could.\" Since then he has carved out his own role supporting the monarch, accompanying her on visits and jollying people up with his off-the-cuff remarks, which have sometimes been near the knuckle. \"You managed not to get eaten, then?\" he told a British student who had trekked in Papua New Guinea, in 1998. He is patron of some 800 organisations, and has carved a niche for himself in the fields of conservation, design and developing life skills among youngsters. At the grand age of 90, however, he has finally decided to take a step back. \"I reckon I\'ve done my bit. I want to enjoy myself a bit now, with less responsibility, less frantic rushing about, less preparation, less trying to think of something to say,\" he told the BBC. \"On top of that my memory\'s going, I can\'t remember names. I\'m just sort of winding down.\" Paying tribute to the duke this week, Prime Minister David Cameron said he had been \"a constant companion and a source of rock-solid strength\" to the queen, and had served the British people \"with an unshakeable sense of duty\". He said Britons found the duke\'s \"inimitable\" down-to-earth style \"endearing\" and the country owed him a \"deserved debt of gratitude.\" Buckingham Palace has released 90 facts about the duke to mark his birthday, including that he drives a liquid petroleum gas taxi around London and designed the Inter-University Tiddlywinks Championship trophy. The formal marking of his 90th birthday will be a service of thanksgiving at Saint George\'s Chapel in Windsor Castle, attended by the royal family, with a reception to follow. A special commemorative coin has also been produced. The no-frills celebrations are very much in keeping with his character. As a youth, the prince was \"very boyish, but great fun, always great fun and very kind,\" his cousin Lady Myra Butter said. \"He hasn\'t really changed much as a person at all, I don\'t think. He just gets on with it. That\'s his motto. Just get on with it.\"