Modern, 1901-present

Modern era is punctuated by the First World War, Interwar, Second World War, Post-war, New Elizabethan, New Carolean ages.

The First World War (1914-18) forced Britain to export much of its gold and silver reserves to the US as repayment for war loans, and Britain reduced the fineness of its silver coinage from the 0.925 sterling standard to 0.500 or 50% in 1920. 

As a result of the economic strain of fighting yet another major war (Second World War, 1939-45), Britain was forced to undergo one last final debasement of its circulating coinage, when silver was replaced entirely by cupro-nickel in 1947.