It’s nearly ten years since I left the Liberal Democrat Party, and nine since I first voted Labour in an election. I’ve been a member for a comparatively modest five years – I was never eligible to be in Young Labour, don’t have a “where were you?” story from May 1997, and I’m completely in the dark about what it’s like to be in the Labour Party when it’s in government. I can only hope the last of those changes before I join Decidedly Elderly Labour.

The shortest version of the reason I ended up in the wrong party is that I grew up in a solid blue area, in a family that was either Conservative or apolitical, and with a much greater love of nineteenth-century fiction than late twentieth-century reality. My politics as a teenager emerged as many people’s do – over single issues. I was quick to outrage over violations of individual rights, like the death penalty, while remaining sheltered from structural, economic forms of injustice, as a young person in those parts of the country often referred to as “leafy” all too easily can. I honestly don’t think I knew what a trade union was until I was in my twenties.

In fact, as the daughter of a single mother earning a teacher’s salary, in an all-female household, it was feminism that first taught me that bad systems were as culpable for the world’s evils as bad people. This would eventually lead to an equivalent understanding of class politics, but it hadn’t yet crystallised when, at 23, I trotted off to my first Proper Job – organising the Liberal Democrats’ internal campaign to recruit more women to Parliament. I had already been a student union sabbatical officer – the Women’s Officer, obviously – in a team where friends and colleagues were fiercely pro-Labour. From them I had begun to understand what is laughably obvious to me now: that the grassroots community of a political party is far more diverse in its views than the front bench; and that you can’t reasonably judge a party’s true nature with sole reference to its more eye-catching policies at any fixed point in time. But aspects of New Labour, like the plans for 90 days’ detention for terrorism suspects, really did alienate me.

It was obvious from my earliest days at Lib Dem HQ, though, that something wasn’t right. I soon learned that I wasn’t going to be given the one tool that would help me actually achieve my objective of increasing women’s representation in the party – All-Women Shortlists. And not by some oversight, but because most of the party was, at the time, ideologically opposed to them. Some local activists were openly hostile to efforts to increase women’s dire representation in their party, even at the level of women-only training or women-only mailings. Since my job was, in essence, a form of positive discrimination, this made life somewhat difficult.

After walking around the building silently fuming one too many times, I finally began to realise I was battling a core part of the ideology, not an unfortunate habit. There were exceptions, but too many of the people around me were angrier about ID cards and cannabis being illegal than they were about deeply-rooted social and economic inequality. When they voted through the now-infamous policy of anonymity for rape defendants in 2006, I knew my days as a liberal were numbered. I let my membership lapse while still working there, and then left to study law. I didn’t make a show of the fact I was no longer a supporter – nobody had wronged me; I had been the one to make a mistake.

My decision surprised precisely nobody. In fact too many of my Labour friends were able to say, quite correctly, that they had always predicted it. I voted for Ken Livingstone, Labour’s chosen mayoral candidate, a year later but crucially, didn’t join for another couple of years. As with a relationship gone wrong, I needed a break. I knew I wanted to be part of the grassroots this time, so when it felt right – and long before a leadership election was in sight – I joined Hackney North and Stoke Newington CLP, later supplanted by Camberwell and Peckham. I’ve hence had the chance to back two of the standout women MPs who used to symbolise for me what the Liberal Democrats were constitutionally unable to achieve.

As the Labour Party goes through the process of vetting new joiners – the so-called ‘purge’ – all of this has been back on my mind. I have more reason than many to understand that people’s politics, or their understanding of how to categorise their politics, changes. I’m sure even now that there are people languishing in political parties that they know don’t reflect their values, for all kinds of reasons – because they’ve built friendships, because they’ve been offered opportunities, because it’s always hard to admit you’ve been wasting your time.

And yet I find myself mystified at the idea it’s controversial that the Labour Party hasn’t accepted everyone who has applied. It is entirely clear to me that if you backed another party, particularly with the kind of tribalist glee that dominates political Twitter, just three months ago, then you can’t be surprised if Labour gatekeepers – who are not psychic – err on the side of caution in deciding whether to let you vote in a contest that will influence the entire future direction of our party and movement. Entryism – people joining specifically to vote in a way that they hope will damage us – isn’t a figment of fevered imaginations at Brewers’ Green, but a past and present reality. If there is one thing that we all still agree on, surely it it that leadership of the Labour Party is a decision only for those who support it?

But I also now wonder if I was lucky to be allowed to join, or at least benefitted from good timing. Nobody ever questioned me, and I’m not naïve enough to think this is because my socialism was luminously apparent from the way I filled in the form. There was no social media where I would have built up a record of support for another party, and I wasn’t part of a sudden influx of new members at a critical time.

Even so, if I were one of those rejected in the last week – having made a genuine but recent conversion – I would understand why. And I would seek to join again in a few months’ time; being denied a vote now is not a permanent rejection, though you wouldn’t know it from much of the coverage. It seems to me that those up in arms have a strange and one-sided view of what it means to be a party member. It isn’t a market, with members as consumers, who may drift off to another provider and come back depending on the deals on offer. Joining as a member or supporter is different from choosing who to back in a general election – there are obligations and not just entitlements. That doesn’t mean leaving your brain, your expertise or your right to dissent at the door. But there must be an expectation, as in all institutions with some claim to be democratic, that sometimes, you won’t get your way – whether that’s on leaders, candidates to campaign for, or policy.

Of course there’s such a thing as a compromise too far for your own conscience. Like all members I reserve the right to be hopping mad with Labour, and to feel disinclined to knock on doors for a while. I understand that some, in extremis, may even choose to leave for a time if they feel they can’t keep giving their money and their endorsement to a direction they profoundly disagree with. But what I cannot imagine ever doing, in any circumstances, is joining another party. Despite the fact a younger version of me once did. Because my values are, at their root, Labour values – and they were never anything else.

If that means I’ve gone native, acquired the zeal of the convert, then so be it. But no, I cannot understand the feelings of those who backed another party just a few months ago, or made efforts to undermine Labour, and now feel aggrieved that they can’t switch political affiliation the way you switch energy providers. And wouldn’t anyone who really puts the common good before avoiding minor inconvenience to the individual – which I take to be a basic Labour value – feel the same?