Rimington's groundbreaking leadership transformed MI5 from a secretive organization into a more transparent and accountable institution. Her decision to publicly identify herself and demystify the service through educational materials helped build public trust in intelligence work. The policies she established created lasting reforms that continue to guide MI5's openness today.
The government's harsh reaction to Rimington's memoir revealed ongoing institutional resistance to transparency, with officials attempting damage control and even considering her arrest. Her exclusion from receiving a peerage, unlike her successor, suggests official displeasure with her post-retirement activities. The controversy surrounding her book publication demonstrated the limits of the openness she championed.