Commonwealth Day was celebrated in March, as it is every year, but what exactly is a commonwealth and where does the term come from? The word itself was first recorded in 1470 and derives from the phrase ‘the common weal’, which meant ‘public well-being’ and so came to be applied to political systems established (ostensibly) for the common good.

There have been various examples of commonwealths in history: one of the earliest was the Polish-Lithuanian Commonwealth, which united those two nations from 1569–1795. Following the English Civil War, England, Scotland and Ireland were governed as an uneasy commonwealth for several years, with Oliver Cromwell and his son as ‘Lord Protectors’. Four of the United States of America – Kentucky, Massachusetts, Pennsylvania and Virginia – are technically commonwealths, as is Australia, whose offical name since 1901 has been the ‘Commonwealth of Australia’. Most recently, the Commonwealth of Independent States, a loose association of former Soviet republics, was founded in 1991.

By far the best-known example, however, is the Commonwealth of Nations, known simply as ‘The Commonwealth’, a voluntary association of independent nations that has evolved out of the former British Empire. When Britain’s colonies began transforming themselves into self-governing dominions, starting with Canada in 1867, the need arose for a new framework to bind together the far-flung entities of the British Empire, but which implied  equality with Britain rather than British domination. In 1884 Lord Rosebery, the future British Foreign Secretary and Prime Minister, referred to the empire as a ‘Commonwealth of Nations’ during a visit to Australia, but it was the South African soldier-statesman, General Smuts, who in 1917 formally advocated replacing the term ‘empire’ with a ‘British Commonwealth of Nations’. This was duly inaugurated in 1931. In 1949, to reflect the emerging post-war, post-colonial era, the word ‘British’ was dropped.

Today’s Commonwealth comprises 54 countries, spread across six continents, with a combined population of over two billion. Most are linked by historical, linguistic and cultural ties, but the club now includes countries such as Mozambique and Rwanda that were not British colonies. All, however, commit themselves to common values: the promotion of democracy, good governance and the rule of law, respect for individual freedoms and human rights, racial and gender equality, free trade and sustainable development. As a result, Commonwealth countries are not strictly considered to be ‘foreign’ to one another but rather constitute what Queen Elizabeth II has referred to as ‘a family of nations.’ This is why diplomatic missions between Commonwealth countries are designated as High Commissions rather than embassies, and why the full title of the British Foreign Office is the Foreign and Commonwealth Office.