By Michael Holden LONDON (Reuters) -The crowning achievement of Britain’s Queen Elizabeth, who died on Thursday after 70 years on the throne, was to maintain the popularity of the monarchy across decades of seismic political, social and cultural change that threatened to make it an anachronism. A dignified, dependable figure who reigned longer than any other British monarch, Elizabeth helped steer the institution into the modern world, stripping away court ritual and making it somewhat more open and accessible, all in the glare of an increasingly intrusive and often hostile media. While the na…