This work investigates the historical and scientific evolution of timekeeping and astronomical observation that necessitated the establishment of a universal prime meridian at Greenwich. Derek Howse, a former head of navigation at the National Maritime Museum, utilizes his expertise in maritime history and horology to document the technical challenges of calculating longitude at sea. He presents a chronological framework that links the development of precision chronometers with the global standardization of time zones.

Experts recognize this text as a definitive, accessible account of the technical and political history behind the Prime Meridian. Readers frequently note the clarity of the prose, which balances complex navigational concepts with engaging historical narrative.