Ever since my arrival in Lisbon, whenever new Portuguese acquaintances discover that I am English they invariably refer to the world’s oldest alliance or to Catherine of Braganza’s role in popularising tea-drinking in England. Their enthusiasm leaves me with a vague feeling of camaraderie that is difficult to explain given my limited knowledge of the story behind these historical headlines. However, whenever I walk the history-drenched, crumbling streets of Lisbon, my senses are both stimulated by the Lusophone world and comforted by the familiarity of the English world as glimpsed through place names like Rua da Cidade de Liverpool or Port brands like Taylor’s. And studying Portuguese, I encounter Anglicisms or sayings inspired by Anglo-Portuguese history. All this hints at a ‘special relationship’ between Portugal and England that has existed for far longer than the US–UK relationship. Now, on the day that the world’s oldest alliance celebrates 630 years, it is finally time to delve into its rich history.

When King Richard II of England and the envoys of King João I of Portugal signed the Treaty of Windsor on 9 May 1386, they could not have envisaged it remaining in force 630 years later. However, Anglo-Portuguese cooperation was not new even in the fourteenth century. Back in 1147, English crusaders stopped off on their way to the Holy Land to help Portugal’s first king, Afonso Henriques, capture Lisbon from the Moors. Burgeoning commercial ties were facilitated through various treaties in the intervening years. Even one of Portugal’s most celebrated victories, over the numerically superior invading Castilian army at the Battle of Aljubarrota in 1385, had help from a small band of English archers. Whilst previous cooperation would have facilitated negotiations, the Treaty was driven primarily by John of Gaunt (the Duke of Lancaster) seeking Portuguese support for his claim to the Castilian throne, which he then pressed through an expedition in July 1386. Although the expedition failed, the impact on Anglo-Portuguese relations and Portuguese history in general were far-reaching as Gaunt left behind his daughter, Philippa of Lancaster, to marry John I and the couple engendered the generation of princes that led Portugal into its golden age of discoveries.

So why has an alliance borne out of immediate political interests endured? Commercial ties were certainly a factor, evidenced, for example, in Philippa of Lancaster’s provision of royal patronage to English merchants to meet the Portuguese demand for cod and cloth in return for wine, cork, salt and oil. However, political expediency was the main driver; as the ancient proverb says, ‘the enemy of my enemy is my friend’. Both countries had on-off rivalries and confrontations with Spain and France throughout their history. In particular, Portugal regularly faced the threat of annexation from Castilian and Spanish monarchs who wielded the weapons of conquest or marriage.

Therefore, an alliance to counterbalance these powerful neighbours made eminent sense and proved decisive at various points: the seven years war when England intervened to help Portugal expel the Spanish and French invaders; the peninsular war where the English joined with the Portuguese and Spanish to defeat Napoleon’s forces; and the First World War where Portuguese troops fought alongside the Allies on the Western Front. In modern times, the enduring strength of the alliance is perhaps best illustrated by the significant material, albeit secret, support that Salazar provided to Britain in the Second World War – such as hosting British bases in the Azores – despite having more obvious ideological affinities with the Axis powers.

Of course, like all good friends Portugal and England have fallen out from time to time. The 1890 British Ultimatum forced the Portuguese to retreat from land, located between its colonies of Mozambique and Angola, that it claimed on the basis of historical discovery and recent exploration but that Britain also claimed on the basis of effective occupation. In the short-term, this national humiliation led to the fall of the Portuguese government, but it was also a factor in the Republican Revolution that brought an end to the monarchy some twenty years later. Thereafter, the pejorative phrase ‘Perfidious Albion’ entered into popular usage in Portugal as a way to refer to its British ally’s treachery and duplicity.

Other ‘misunderstandings’ have also left their mark on the popular imagination and vernacular. The idiomatic expression para inglês ver (literally ‘for the English to see’ but used in the sense of  ‘just for show’ ) comes from the 1830s when the British Empire started clamping down on the slave trade. In response to the Royal Navy boarding Portuguese ships to inspect them for signs of slave smuggling, the Portuguese attempted to throw them off the trail by loading the first ship in their fleet with an innocuous cargo ‘for the English to see’. Amigo de Peniche (literally ‘friend of Peniche’, used to refer to a ‘false friend’) comes from 1589 when an English army landed in Peniche to aid a rebellion against the Spanish occupation of Portugal. The rebels put great hope in these ‘friends of Peniche’, but were badly let down by the English army that rampaged through local villages and ultimately fled when attacked by the Spanish.

Unsurprisingly, 630 years of political and commercial ties have impacted on the cultural life of both nations, which brings us back to Catherine of Braganza and the British national pastime of tea-drinking.  Due to Portuguese trade with China, Catherine was already an established tea-drinker by the time she married Charles II of England. She set a trend at court that quickly spread throughout the English aristocracy, for whom tea became the drink of choice. Drinking habits have been influenced in the other direction too. English merchants established in the Porto area, benefiting from commercial privileges dating back to the Treaty of Windsor, had long added brandy to wines from the surrounding Douro region at the time of shipment to fortify them for the sea voyage to England. As the eighteenth century wore on, they increasingly added brandy to the wine before it had finished fermenting, and the basic Port-making process was born. Since the sweeter and stronger wines that resulted held greater appeal for the English consumer, the Port wine trade flourished. On the bottles and the wine warehouses lining the river in Porto, British influence is still evident today in brand names like Croft or Taylor’s.

Place names are one of the more mundane ways in which Anglo-Portuguese ties manifest themselves. Not only Liverpool, but also Cardiff and Manchester get honourable mentions in Lisbon’s street atlas. The Cemiterio dos Ingleses (the English cemetery) in the Estrela district was the place where Lisbon’s English population was buried from the early eighteenth century after the land was purchased by the local English trading station. The presence of a protestant cemetery in a predominantly catholic city was a frequent source of tension. Not only has the cemetery had its share of drama, but it also has some star quality as the final resting place of Henri Fielding, the author of Tom Jones.

Will the alliance still be in force in another 630 years? Given the ever-increasing pace of change engendered by globalisation, little in the established world order can be taken for granted. The long-term impact of a possible Brexit on Britain’s relations with EU countries, including Portugal, is hard to predict. Will the EU decide to repatriate British expats, including those living in Portugal, for example? However, regardless of wider geo-political developments, given the weight of shared history and political, commercial and cultural ties, as well Portuguese people’s proficiency in the use of the English language, it seems likely that Portugal and the UK will always find more to unite than to divide them. The alliance will undoubtedly endure through my lifetime, so I am glad that I can finally respond to new acquaintances with something more than a quizzical smile.