WILFUL forgetfulness is one of the defining vices of British politics. Resigning can be a great way of laundering your political reputation.

Last week proved no exception. Enter and exit Theresa May – former prime minister, former home secretary, and soon to be the former MP for Maidenhead.

News she is demitting office was met with wall-to-wall dribbling from the establishment press and even some of her political opponents. She is, we’re told, a “good egg”.

It’s been decreed that our stilted ­former PM who led the way in ­mainstreaming the monstering of immigrants, lying about ­human rights, who buggered up Brexit, lost her government its ­majority, ­pandered to the lunatic right in her party and ­bequeathed them an heir and ­successor in Boris ­Johnson was a ­“fundamentally decent” woman animated only by a deep sense of public service and a well of good intentions.

I have questions. I don’t think the world is black and white. Nobody is all good, or all bad. It’s rare to encounter anyone who puts themselves into public life with ­self-consciously malign intentions. But ­politicians should be judged on what they do – and in these terms, May’s “decency” is difficult to find.

As sitting home secretary in 2011, May decided it was a good idea to tell the Tory conference a populist fairy story about how “Labour’s Human Rights Act” was ­working in practice in the field of immigration, ­explaining she’d like the Act to be axed, ­tormenting delegates with three vivid stories about its alleged dysfunction.

“We all know the stories about the ­Human Rights Act,” she said. “The ­violent drug dealer who cannot be sent home ­because his daughter – for whom he pays no ­maintenance – lives here. The robber who cannot be removed because he has a girlfriend. The illegal immigrant who ­cannot be deported because – and I am not making this up – he had a pet cat.”

But she was, in fact, making it up. ­Handcuffing yourself to a Siamese will not dissuade Home Office goons from putting you in their van, and will not persuade ­immigration judges to let you stay in the country. You know that.

Theresa May knew that. But she decided it would be fun to pander to her audience’s prejudices. And at the risk of sounding prim – something the starchy former PM probably approves of – she decided to do so while holding one of the four Great Offices of State.

Priti Patel and Suella Braverman (below) built on and elaborated – rather than departed from – May’s rhetorical legacy.

The National: Braverman has been approached for comment

But it isn’t just words. Among the ­various recent scandals of British public life, Windrush still doesn’t receive the attention it merits. May’s legacy ­cannot – must not – be reckoned with ­without ­factoring this example of what she achieved in public office.

She created a framework for and stood over the ­widespread persecution and ­unlawful ­expulsion of black pensioners from the country they were entitled to call home. This isn’t hyperbole and this is not some ­minor footnote in her political ­career we can wave aside – it should define it.

The story begins with post-war ­migration. Between 1948 and 1973, the Windrush generation landed in the UK mostly from Jamaica and ­Trinidad and Tobago. Adults came for work. ­Children generally travelled on their ­parents’ ­passports. At this time, the British state adopted a light-touch approach to ­documenting these new arrivals.

READ MORE: UK Oil and gas windfall tax loophole 'must be closed'

This fact would lead to tragedy ­almost half a century later, as the children grew into adults, lived and worked and forged families in Britain and all the time ­unaware that the undocumented state the British state left them in would eventually lead to disaster.

What changed everything was the ­“hostile environment” May announced in The Telegraph in 2012. She promised to give “illegal migrants a really ­hostile ­reception” in the UK. The “hostile ­environment” had different elements to it. Some was brutal PR.

The Home ­Office ­notoriously piloted a scheme in the ­summer of 2013, sending vans bearing the following legend around six ethnically diverse London boroughs: “In the UK ­illegally? Go home or face arrest”. These threats and menaces were accompanied by the boast that there had been “106 ­arrests last week in your area”.

But the special genius of May’s ­“hostile environment” was to turn all of us into ­immigration enforcers. The new ­framework placed an emphasis on ­individual enforcement and ­individual documentation. The Home Office ­effectively outsourced and privatised ­responsibility for social surveillance. Want to take up a job? Your employer is now responsible with superintending your immigration status. Want to go to university? Produce your papers, please. Want to rent this flat? I’m going to need to see some proof you have the right to remain. Even the NHS was drafted into the project.

When this need to prove your immigration status met the often ­undocumented Windrush generation, tragedy ­ensued and hundreds of people found ­themselves on the receiving end of the new ­intolerance.

Take the case of Albert Thompson. The Guardian first broke his story in 2018. ­Albert arrived in the UK from ­Jamaica with his mother in the 1960s. He was just a teenager at the time. She went on to work as a nurse.

He built up a life for ­himself here, working and making a ­family. Albert had lived in Britain for more than 44 years when he was confronted by the hostile environment May’s policies helped create.

The first sign something was wrong wasn’t a detention van pulling up ­outside his house or an unexpected knock at the door – but when he attended an NHS ­hospital for treatment. He’d been ­diagnosed with cancer.

When he attended his first radiotherapy session at a London hospital, he was taken aside by an NHS administrator with an ultimatum.

Unless he could produce a British passport, they told him his treatment would cost him £54,000. He didn’t have a ­British ­passport, and he didn’t have £54,000. “It’s like I’m being left to die,” he said.

There are many other appalling stories about the impact these changes had on other elderly Afro-Caribbeans who fell under Home Office suspicion. There was Paulette Wilson. She had lived in the UK for 50 years when a letter arrived, informing her that she was an illegal immigrant and had six months to return to Jamaica – a country she left at 10 years of age.

She was detained and spent a week in Yarl’s Wood before winning a late ­reprieve just before she was put on a plane at Heathrow to be transported “back” to an unfamiliar country. Others were not so lucky.

The Home Office has now ­admitted it wrongly deported or detained at least 164 people originally from ­Caribbean ­countries who were living in the UK ­entirely lawfully for decades.

Some 12,000 people wrongly ­classified as ­illegal ­immigrants have now secured passports or other documentation ­confirming their immigration status. The British state ­effectively punished these ­people for the state’s decision to adopt a ­document-light approach to the ­Windrush generation who arrived in the UK between 1948 and 1973.

Others were sacked from their jobs, ­unable to seek employment, ­rendered ­homeless and denied any benefit ­entitlements. It is difficult to imagine the sense of precarity these people ­experienced.

The National: Former prime minister Theresa May has announced her decision to quit Parliament (Hannah McKay/PA)

It was Theresa May’s (above) home ­secretary who ended up carrying the can ­for these foreseeable consequences of her ­immigration policies. Attempts were also made to blame overzealous junior Home Office officials, as if the tone – like the policy – wasn’t set at the top.

Since stepping down as PM, May has written a slight and self-serving book ­entitled The Abuse Of Power. The ­Windrush scandal merits only a few ­pages in this dreary justification of her time in politics.

Of the “hostile environment” she helped establish, May blandly reflects “in retrospect, it was not a good term to use”.

“It was suggested at a time when it was clear that it related to people [who] were here illegally, but of course, it became a term that was used in relation to a generation who had every right to be here.”

Missing here is any real sense of moral responsibility or political gravity – any sense of reflection on her central role in creating the circumstances which made all this misery possible. It’s remarkable what centrist airheads are prepared to ­forgive and forget, if they’ve decided someone is “fundamentally decent”.

READ MORE: Politicians can spin all they like, but the public wants peace in Gaza

Fundamentally indecent policies which wrecked hundreds of people’s lives are ­reduced to a footnote in flattering ­political obituaries – unimportant in the grand scheme of things, minor details in apparently worthy career.

Who needs a memory hole when our political system is prepared to forget ­inconvenient facts all on its own, without any encouragement or coercion?