Crowds celebrate Queen Elizabeth's 90th birthday walkabout

By Georgina Cooper WINDSOR, England (Reuters) - Queen Elizabeth greeted thousands of well-wishers from across Britain and beyond as she celebrated her 90th birthday on Thursday, demonstrating the world's oldest monarch's intent to keep doing the job she has performed for more than six decades. Usually the queen's birthday passes with little ceremony but to mark Thursday's milestone a beaming Elizabeth, attired in a light green outfit, mingled with crowds during a lengthy walkabout near her Winds