This paper charts the history of Global Satellite Navigation Systems (GNSS) from the earliest days of the ‘Space Race’ in the 1960s and 1970s to the latest plans for modernisation of existing systems and the development of new systems yet to be deployed or become operational. The paper is based on lectures and presentations given by the author to postgraduate students at The University of Nottingham, students on the RAF General Duties Aero-Systems Course at the Air Warfare Centre, RAF Cranwell and to a number of RIN, RAeS and IEE Branches and to local aviation groups.