LONDON: Queen Elizabeth II’s eight grandchildren mounted a vigil around her coffin on Saturday, hours after King Charles III and his heir Prince William staged an unscheduled London walkabout to thank those queueing overnight to pay their last respects. William and his estranged brother Prince Harry led the 15-minute vigil inside parliament’s Westminster Hall, which has hosted tens of thousands of mourners since the late queen began lying in state there on Wednesday. The grandchildren, aged from 44 to 14, stood silently with their eyes lowered as members of the public filed past. Harry — who s…