Why British ambassadors are still sent to a royal court, not a government
Envoys to London are formally accredited to the Court of St James's, a relic of the idea that an ambassador is the monarch's personal stand-in. Commonwealth countries, sharing a head of state, skip ambassadors entirely and swap high commissioners instead, introduced by a simple letter between prime ministers.
An ambassador is a state's senior representative in a foreign country or at an international body. The host lets the mission control an embassy, whose premises, staff and cars usually enjoy diplomatic immunity. The host must approve the chosen person first and can later declare them persona non grata, which normally means recall. The English word traces back through Anglo-French to an Old High German term for service and was first recorded around the 14th century.
Envoys are ancient; the office as we know it is not. Classical Greek cities used a proxenos, a local citizen who looked after another city's interests. The modern system grew out of Renaissance Italy from about 1300, where small, vulnerable states used resident ambassadors in the 15th century to gather information and protect themselves. The Italian Wars carried the practice across Europe, and rules on ambassadors' rights set in the 16th century still echo today.
The Congress of Vienna in 1815 fixed three ranks: ambassadors, envoys and chargés d'affaires. The 1961 Vienna Convention, effective from 1964, made ambassadors the top rank with plenipotentiary powers, meaning full authority to act for their government. That is why most carry the grand title Ambassador Extraordinary and Plenipotentiary; extraordinary once distinguished envoys sent for a specific mission from those resident in post. Envoys ranked below ambassadors until the 1960s, when the last legations became embassies. Countries wishing to keep relations cool can post only a chargé d'affaires.
Variants abound. The Holy See sends nuncios, equal in rank to ambassadors. An ambassador-at-large may cover several countries, a region or an organisation such as the United Nations, or advise on a particular issue. In some foreign services, ambassador is also simply a career grade, held even while working at home. The day-to-day job has broadened too: protecting citizens abroad, smoothing trade and cooperating against trafficking and bribery.
Source: Ambassador
