The most senior official at the Home Office is resigning after a 33-year civil service career. Dame Helen Ghosh - who has led the department since January 2011 - will take up the role of director general of the National Trust. She is one of a number of permanent secretaries who have left the civil service this year. She said she was "torn about leaving" but the chance to work for the National Trust was "a rare opportunity". Dame Helen Ghosh has worked in Government since 1979 for both Conservative and Labour Ministers. Her tenure included controversy at Defra over the Rural Payments Agency and more recently at the Home Office with concerns over the Border Agency. Chris Bowlby assesses her career and the qualities that propelled her to the senior ranks in Whitehall and asks what they tell us about the approach she is likely to bring to her new role. Producer: Ian Muir-Cochrane.