The last couple of weeks of the election campaign - and the erroneously narrow polls which highlighted the role of The Queen in the event of a hung parliament - brought to the attention of the public a man who has held arguably one of the most important jobs in Britain since 2007, but who remains largely unknown. He's Sir Christopher Geidt, Private Secretary to The Queen. He is her adviser on political and constitutional matters, and her line of communication to the Government. But who is he?

Presenter: Mark Coles