In the New Year, what started with an offer of a six-month stint as a Commons researcher will turn into half a lifetime for me – 30 years of working continuously in Parliament under six prime ministers, over four decades since 1987. We’ve seen the end of the Cold War, the end of history, the end of the end of history, and now maybe the end of the liberal world as we know it.

For the first 18 years, I worked with Harry Barnes, the MP for North East Derbyshire who berthed in the Socialist Campaign Group alongside Ken Livingstone, Tony Benn and Jeremy Corbyn. I occasionally attended their weekly meetings, which were small in numbers but large in ambition, although I never expected Corbyn would ever become Labour leader.

An early priority in the 1980s was opposing the poll tax and forming campaign groups across the country. We unsuccessfully urged Labour to embrace broad-based campaigns to prevent Militant from monopolising the movement. I had briefly joined Militant as a teenager in the 1970s and uneasily shared an office with with the staff of their MPs: Dave Nellist and the late Terry Fields and Pat Wall. Harry Barnes was the first to clock that millions would be disenfranchised by the poll tax and later designed the modern, rolling electoral registration system.

From the 1990s my priority was opposing the hard left’s often outrageous positions on Northern Ireland. I worked with British and Irish activists in holding vigils for those murdered by the IRA in London, and in picketing Sinn Fein conferences in Ireland. Activists worked with Irish parties and unions under the patronage of Irish president Mary Robinson to deny legitimacy to terrorists and their apologists. We took up the cause of Bloody Sunday and once held a presence for peace at a Troops Out Movement march in Islington with placards saying “No more Bloody Sundays, Mondays, Tuesdays” to condemn all illegitimate violence. A Republican flute band passed by chanting “I-I-IRA” to a militaristic drumbeat.

Theresa May reassures Northern Ireland about Brexit negotiations

We adopted and amplified a then controversial revisionist position that partition was a product of long divisions and ending it was not the solution. A united Ireland based on coercing, or to use the euphemism of the time persuading, the Protestants would probably cause greater violence. We built dialogue with unionists, which was deeply unpopular with some, but essential to the eventual peace deal. Our cross-party peace group gave a platform to David Trimble, leader of the Ulster Unionist Party, at a Labour conference and I recall seeing people’s jaws drop in alarm.

Oddly, parts of the British left were more nationalist than the Irish left, with which I worked, and some British leftists trotted out trite phrases like distinguishing between the violence of the oppressed and the oppressor. Standing outside the Sussex Pub in Covent Garden with the sister and mother of David Heffer, a young man cruelly murdered in an IRA bomb there, put such thinking into perspective. Eventually, Labour turned on the nonsense of Troops Out and anti-partitionism by backing John Major’s brave peace process, a move then taken up with gusto by Tony Blair. Those who shared Sinn Fein’s analysis were mercifully defeated on what was then the biggest security issue for the country.

Much of their logic-chopping was transferred to wider anti-war campaigning from the first Gulf war in 1990-91, when Harry and I secured an Iranian Boeing 747 to take blankets to Kurdish people huddling in the freezing mountains. Harry and I amicably differed on the invasion of Iraq in 2003 but then discussed what to do next given that the war hadn’t been stopped.

We had supported Northern Ireland groups trying to overcome religious differences in favour of overarching interests such as class. We sought such partners in Iraq, and formed Labour Friends of Iraq. This backed Iraqi democrats and slammed Stop the War Coalition leaders when they insulted Iraqi trade unions, of which Harry and I are honorary members, and when they implicitly supported insurgents who shot election workers and tortured a union leader, Hadi Saleh, who we had previously invited to the Commons.

We then organised a Labour movement delegation to the Kurdistan region a decade ago. (A Kurdish Communist leader explained they had no bourgeoisie and asked if they could they borrow ours.) Captivated by what I saw, I helped form the all-party parliamentary group on the Kurdistan region to boost the many connections between our countries.

I had became deeply embroiled in the controversies of Ireland and Iraq only accidentally – but it forced me to confront received wisdom on the left, some of which I had shared. I tried to take new facts to logical conclusions, as I saw them, even if it meant breaking taboos and sometimes losing friends. I have long been on the right of the left and increasingly despair of the so-called left which embraces tin-pot anti-imperialists, as in the recent lionisation of Fidel Castro – If Cubans couldn’t freely leave their country, they lived in a prison.

I’ve been very lucky to have had a varied and perhaps valuable half a lifetime in Westminster. Having visited Kurdistan and Iraq 25 times in the past decade, I understand better now what makes our parliamentary democracy an important model for resolving conflict and managing interests through the rule of law. And having worked with parliamentarians across the spectrum, I know that most follow a vocation with degrees of verve and passion – and that vice and virtue do not follow party lines.