After the Second World War, the British government invited thousands of people from the Caribbean over to the UK to help rebuild the country.

The new arrivals, the first of whom were brought over in the HMT Empire Windrush, had been granted full British citizenship in 1948 as members of the Commonwealth.

Now, after decades living and working here, some members of the “Windrush generation” are being threatened with deportation – apparently because they can’t provide the documents to prove how long they’ve been in the UK.

It was reported last week that when Theresa May was Home Secretary in 2010, her department destroyed thousands of “landing cards”. For some, these cards would have been the only proof of exactly when they arrived in Britain.

At Prime Minister’s Questions the following day, Jeremy Corbyn said the government had been “callous and incompetent.” But Mrs May shot back, revealing the decision to destroy the documents was actually taken in 2009, when Labour were in government.

So who’s really to blame? And would the landing cards have actually made a difference to someone threatened with deportation?

The timeline

2009 – Destruction of documents begins

In June 2009, the UK Border Agency approved the business case for disposing of millions of paper records.

The Home Office told us that it was then that the landing cards – or “registry slips” as they’re officially known – were earmarked for destruction. The work began in December of that year.

Alan Johnson was the Labour Home Secretary at the time. When asked if he knew that the registry slips were being destroyed, he said: “No, it was an administrative decision taken by the UK Border Agency.”

2010 – Registry slips destroyed

Although the decision was made in 2009, it wasn’t until October 2010, when the Conservative-Lib Dem Coalition government were in power, that the registry slips were actually disposed of. The Home Office described this to us as an “operational decision”.

Theresa May was Home Secretary at the time, but we haven’t seen evidence either way to suggest that she knew about, or signed off, the decision.

2012 – Hostile environment policy introduced

In May 2012, Theresa May declared: “the aim is to create here in Britain a really hostile environment for illegal migration.”

And sure enough, the Immigration Act 2014 brought in new powers to help the Home Office and other government agencies make life difficult for illegal migrants.

But many have claimed that those same policies have been unfairly damaging and intrusive to people who are here legally, including the Windrush generation.

Last week, Jeremy Corbyn called for the prime minister to repeal the legislation, and urged the government to “stop the rhetoric which is blaming immigrants for problems they didn’t create.”

Why were the documents destroyed in the first place?

FactCheck understands that the UK Border Agency decided to destroy a raft of personal documents in 2009 because of its legal obligations under the Data Protection Act 1998.

The Act sets out eight data protection principles – the fifth rule is particularly relevant here. It says that personal information mustn’t be kept for longer than is strictly necessary.

Are the landing cards really that important?

A Home Office spokesperson told FactCheck that “In the judgement of UKBA [UK Border Agency] the information on the slips was of limited value and not sufficient to justify continued retention.”

They went on: “So it would be misleading and inaccurate to suggest that registration slips would therefore have a bearing on immigration cases whereby Commonwealth citizens are proving residency in the UK.”

But is it really that simple?

We asked Damian Krushner, a barrister practising in immigration law (who was also a Labour councillor between 1998 and 2002), for his take: “The Home Office is really straining the meaning of ‘limited’.

“Their view is that the landing cards don’t in themselves show continuity of UK residence and can’t alone provide enough evidence for a biometric visa or citizenship grant. That would usually be right, but in conjunction with other evidence of UK presence since, they could certainly evidence the claimed UK length of stay.”

Adrian Berry, a barrister at Garden Court Chambers and Chair of the Immigration Law Practitioners’ Association, agrees: “It is misleading to suggest that landing cards have no value; the cards record the arrival of a person, the date of arrival, and where the person was travelling from.

He goes on: “Often they are the first official UK record of a person’s existence. Like a like UK birth certificate they tell you when a person’s presence is first recorded in the UK. They serve to prove when a person arrived and create the foundation for her or his personal account of the life in the UK thereafter.”

So those landing cards, alongside other documents, could help someone threatened with deportation to build their case. But what about people for whom the landing cards were the only remaining record of their arrival in Britain?

That’s the situation facing a number of Windrush migrants – many of whom came over on their parents’ passports or who have lost their official documents.

Damian Krushner again: “The historic relevance is that the migrant would have picked up more visa rights on entry depending on whether they arrived before the 1962, 1968 or 1971 Acts came into force.

“The question of access to public funds, public services and the issuing biometric visas as a gateway to these might well depend partly on the date of arrival and the landing card evidence.”

He says: “The number of real world applicants for whom a landing card would materially alter their status now is very low – but not zero.”

Would this be happening if the government hadn’t introduced the hostile environment policy?

It’s possible that when the UK Border Agency decided to destroy the landing cards in 2009, they were indeed of “limited value”, to use the Home Office’s phrase – but when the “hostile environment” policy came in four years later, they suddenly took on new significance.

Adrian Berry gave us his view: “The destruction of the landing cards made the lives of those affected more difficult.

“But in the context, it was the hostile environment policy of requiring proof of immigration status to access hospital treatment, benefits, and the like, to which the Windrush generation were and are entitled, coupled with a Home Office suspicious turn of mind towards those who sought to prove their entitlement, that interfered with people’s ordinary lives so grossly.”

Damian Krushner points out: “It was not considered much of an issue before the hostile environment but there were isolated cases even before that.

He added: “Another unmentioned aggravator was a 2012 change, whereby those with long UK residence but no proven visa [used to be able to] gain settlement straight away. Now they must complete 10 years and four visas to gain settlement (with no interim access to public funds).”

FactCheck verdict

Both Labour and the Conservatives have accused each other of being responsible for the destruction of Windrush landing cards. The decision to dispose of them was taken in 2009 under Labour (although the then-Home Secretary says he didn’t sign it off). The actual destruction of the documents took place under the Conservatives, when Theresa May was Home Secretary.

The documents were destroyed as part of the UK Border Agency’s legal obligations under the the Data Protection Act. At the time, the Border Agency didn’t consider the documents to be of sufficient value to keep hold of.

Only later – in 2013 – was the “hostile environment” policy introduced by the Conservative-Lib Dem Coalition. Additional changes in 2012 added to the pressure on migrants in the UK.

Had they not been destroyed, the landing cards could now be used alongside other documents to help someone threatened with deportation to build their case for staying. It gets trickier when we talk about people who have no other record of their time in the UK.

The number of people for whom a landing card would materially alter their status now is very low – but not zero.

Nevertheless, it seems likely that the destruction of the landing cards would not be a significant problem for the Windrush generation if the “hostile environment” policy hadn’t been introduced.