On 6 December 1921, a group of exhausted British and Irish politicians and lawyers met in Downing Street to put their signatures to the Anglo-Irish Treaty.

The Treaty was a document designed to end a murderous dirty war in Ireland and achieve Irish independence from English rule after centuries of often violent struggle. In fact, it triggered a bitter civil war between the Irish themselves, but eventually paved the way for the Ireland of today: a modern and prosperous state making its own way in the world free from domination by an overbearing neighbour.

As talks between Britain and the EU enter what we are assured is the final furlong, poised between a deal and a total rupture – with Anglo-Irish relations once again one of the sticking points – the Treaty those men hammered out a century ago offers some surprising and striking parallels.

The historical background to the Treaty was the long and sad saga of British rule over the island of Ireland, and the fitful but persistent attempts by the Irish to end it and achieve freedom and independence. In the opening years of the 20th century, that struggle had entered a decisive phase.

Britain’s Liberal government, depending on the support of Irish nationalist MPs for its Commons majority, was preparing to introduce Irish Home Rule.

The measure was violently opposed by the Protestant majority in the northern province of Ulster, supported by the Tory opposition at Westminster. The Ulster unionists organised para-military formations armed with illegally imported German rifles to resist what they saw as “Rome rule”.

For their part, the nationalists in southern Ireland also organised paramilitary units armed with German guns – though on a smaller scale. In the summer of 1914, Ireland was teetering on the verge of civil war. The shots at Sarajevo precipitated a greater European war, and hundreds of thousands of Irishmen, north and south, Catholic and Protestant, joined the British army to fight for the rights of small nations to resist oppression and forge their own future.

A minority of republican nationalists in Dublin, by contrast, saw “England’s difficulty as Ireland’s opportunity” and began to plot an armed insurrection while the Great War was in progress. At Easter 1916, this rising took place when strongpoints in the city were seized and an Irish republic proclaimed. It took a week of bloody fighting that left much of central Dublin in ruins before the rising was suppressed and its leaders arrested.

The execution by firing squad of the Easter Rising’s leaders after courts martial was the fatal mistake that alienated most Irish people from London’s rule, and led to a clean sweep by the nationalist Sinn Féin party – apart from in Ulster – at the 1918 general election that followed the war. Sinn Féin refused to sit at Westminster and set up their own Parliament – the Dail – in Dublin.

The party’s armed wing, the IRA, opened a violent campaign against British rule with the assassination of policemen and administration officials. London responded by drafting in hardened ex-soldiers, the notorious “Black and Tans”, to fight a vicious war of murders, reprisals, raids and torture in Dublin and across the Irish countryside.

By mid-1921 this “dirty war” had reached a stalemate. Government in Ireland was paralysed, Sinn Féin tribunals had replaced official courts, and an intelligence network run by a guerrilla leader of genius, Michael Collins, had thoroughly penetrated Dublin Castle, the centre of British rule. At the same time, the IRA were battle weary, short of funds, and with many of their leaders in jail.

After a savage “Bloody Sunday” of violence when Collins’s gunmen shot 14 British intelligence agents in their beds, answered by the Black and Tans killing a similar number of Gaelic Football fans at random, peace feelers were extended by both sides. Following cautious preliminary talks involving Sinn Féin’s political leader, Eamonn De Valera, and British Prime Minister David Lloyd George, a delegation of Irish “plenipotentiaries” was nominated to attend peace talks in London.

What, if any, lessons can be learned from this history as the Brexit negotiations reach their climax?

The wily De Valera made sure that his reluctant rival Collins was one of the delegates, foreseeing that compromises unacceptable to hard-line republicans would have to be made, and that Collins, rather than he, would get the blame. Collins was accompanied by Sinn Féin’s founder, Arthur Griffith; a Protestant former British soldier, Robert Barton; a lawyer, Gavin Duffy, radicalised by his defence of the Easter Rising martyr Roger Casement; and a tough Easter Rising and prison veteran, Eamonn Duggan. The delegation secretary was Barton’s cousin Erskine Childers, a half English imperialist turned bitter republican, and author of the classic sailing spy thriller The Riddle of the Sands, who had run guns into Ireland on his yacht before the war.

The British team at the talks was equally formidable. It was led by the Liberal-Tory coalition Prime Minister David Lloyd George, a Welshman who understood the nationalist aspirations of his fellow Celts, and who was a cunning and completely unprincipled negotiator. LG was supported by his friend and rival Winston Churchill, who had lived in Dublin as a child, opposed the Ulster Unionists as a Liberal minister, yet was an ardent British imperialist with a belligerent, combative personality. Churchill was backed up by his bosom drinking buddy, the acerbic and brilliant legal brain and wit F E Smith, now Lord Birkenhead, a veteran Ulster Unionist. Finally came the gentlemanly diplomat Austen Chamberlain, “who always played the game and always lost it”, lookalike son of radical Liberal turned Tory imperialist Joe Chamberlain, and elder half-brother of future PM Neville Chamberlain.

There was an almost surreal atmosphere to the talks, with Collins – who only weeks before had been a hunted terrorist with a price on his head – hobnobbing with the prime minister and sharing with Churchill the friendship of the beautiful American artist Hazel Lavery, frisky wife of the Irish portrait painter Sir John Lavery. But as the discussions dragged on, personal warmth – as well as poisonous rancour – grew between and within the parties. Collins, the son of an Irish peasant farmer, and Churchill, the British aristocrat, discovered an unlikely mutual bond as ruthless and clear-eyed power brokers, while the moderate Griffith derided the austere and extreme Childers as a “bloody Englishman”.

The rocks upon which the talks almost foundered were – as with Brexit – the extent and nature of the remaining ties with Britain once Ireland had cast loose from the mother ship. London insisted on Ireland remaining a Dominion of the British Empire, thereby owing an oath of allegiance to the King, while the Irish held out for a full republic. Also, as with Brexit, the position of Northern Ireland was a sticking point. In the end, after much toing and froing between London and Dublin, and more frothing and bluffing threats of renewed war from Lloyd George, a compromise was reached.

Ireland was to be a “Free State” – somewhere between a Dominion and a Republic – and Northern Ireland was to be allowed to opt out of the new state. Also – analogous with disputes over fishing with the EU – the Royal Navy was to be permitted to use Irish ports for a period. Although wrangles over oaths to a monarch and the meaning of “Free State” may seem arcane or footling, in Ireland, where words matter so much, they caused a new river of blood to flow. As Birkenhead signed the treaty, he told Collins: “I may have signed my political death warrant”. “I may have signed my actual death warrant”, the Irishman replied. He was right.

The legacy of the Civil War was a lasting one that has lingered in Irish politics until today

Back in Dublin as the Dail debated the treaty, bitter rifts opened between former friends and comrades and even between blood brothers. In January 1922, a narrow majority – 64 to 57 with four abstentions – voted to accept the treaty. Led by De Valera, the Intransigent Republicans left the Dail and repudiated the Free State government as illegitimate. Collins justified his acceptance of the Treaty as giving Ireland “the freedom to achieve freedom”. It was, in other words, a half-way house, but was the most that could be got at that moment, given the impoverished and exhausted state of Ireland and the power of the British Empire. In the fullness of time, Collins predicted, complete freedom – a republic – would be attained. Once again, he was right.

As Free State soldiers took over Dublin Castle and other buildings and barracks from the British, Irish Republicans rebelled and Civil War began. The conflict would take the lives of Griffith – who died of a heart attack – Collins, assassinated in an ambush in his own County Cork; and Childers, shot by a Free State firing squad of fellow Irishmen. The power of the Free State – aided by artillery borrowed from the Brits – crushed the Republicans; the Free State proved far bloodier than the British in executing scores of dissident Republicans; and even the stubborn De Valera eventually admitted temporary defeat and ended his boycott of the Dail.

But the legacy of the Civil War was a lasting one that has lingered in Irish politics until today. Until the recent revival of Sinn Féin, Ireland’s two main governing parties, Fianna Fáil and Fine Gael, were directly derived and descended from the warring factions who supported or opposed the Treaty and fought the Civil War, even led by the children and grandchildren of the original warriors. After De Valera led his Fianna Fáil followers back into the Dail and won an election he wrested back the use of the ports from Britain, steadfastly refused to take an oath to a British monarch, remained strictly neutral in World War Two, and even paid a condolence visit to the German embassy after Hitler’s death. But it was the rival Fine Gael party that finally declared Ireland a republic in 1948 – albeit one still shorn of the six counties of Ulster.

What, if any, lessons can be learned from this history as the Brexit negotiations reach their climax?

Apart from the supreme irony that an “independent” Ireland has exchanged domination by one foreign power, Britain, for another: total subservience to the EU; can Britain take a leaf from the book of its old enemy, Michael Collins, and attain the freedom to achieve full freedom from an overbearing European Union?

For if, with the pressure of an economy shattered by Covid-19, our negotiators agree to EU demands limiting our independence over fishing, trade, and Northern Ireland, that does not preclude us from following Ireland’s example and demanding and achieving full freedom in the future. For tomorrow is another day, as they say.