Acting head Joseph Clancy says he has tried to establish a culture of trust within the service following series of embarrassing breachesSecret service boss Julia Pierson resignsA handy guide to the agency’s most famous blundersThe acting head of the US secret Service said on Wednesday that the agency charged with protecting the president had been “severely damaged” by harmful lapses, including allowing a knife-carrying man to jump a fence and run into the White House in September.Joseph Clancy told the House of Representatives Judiciary Committee he had sought to establish a culture of trust within the Secret Service since replacing Julia Pierson, who resigned under fire as director on October 1.