An immigration officer takes part in a raid on suspected undocumented migrants. Lawyers say up to 20 officers attend dawn raids against their clients.

Without due process: How Britain deported 50,000 students – part two

Without due process: How Britain deported 50,000 students – part two

To read the first page of this report, click here

If the fraud allegations were a means to push down immigration numbers, TOIEC offered a useful mechanism by which to do so. After all, the tests were very popular and widely used. They were recommended by the Home Office and provided the only same-day results service available – considerably shorter than the 15-20 days students usually had to wait.

The firm that runs them, ETS, is the largest and most well respected English language test firm in the world. Their tests are recognised in over 130 countries, from schools and government departments to medical and licensing agencies.

What led the Home Office to believe that this wasn't just a case of fraud in one test centre, but a widespread network of abuse across many institutions? It’s hard to tell. The Home Office evidence is not reassuring. In fact, there isn't any – except for hearsay. In all the cases which have gone before the courts, the Home Office only bothered to supply two witness statements, both from members of its staff.

One witness testimony describes how the Home Office reacted to the Panorama report and is not really pertinent to the allegations of fraud themselves. The second describes a trip by a Home Office delegation to ETS' headquarters in the US.

When the Home Office team arrived, the company told them it had a new piece of biometric voice identification software which it could use to test the voice files from the tests for fraud. The software wasn't ready to be fully rolled-out yet, but the firm thought it could be used retrospectively to help the Home Office with its investigation.

There were concerns about the software's ability to assess voice patterns. Would it be thrown off course by regional dialects, short samples, background noises or the hum of air conditioning in the test centre?

If there were doubts, the Home Office official was assured by the answers he heard. He insisted there was only a two per cent error rate and that the voice identification had been double-checked by staff at ETS in batches of 300-400. They confirmed 80% of the results.

New biometric software was used to test voice samples from the tests

This account of what happened at the ETS headquarters in America is the only piece of evidence the Home Office has provided for the 48,000 people it is accusing of fraud.

The testimony is perfectly compelling. But it is nonetheless hearsay evidence, concerning very new technology being used on large, complex data sets half the world away. We have not heard these voice files or been able to assess the software. We cannot evaluate the testing process or even know that it really took place. We don't even have the word of the person who launched it. We only have the word of someone who spoke to the person who launched it.

I have sent a series of questions to ETS asking for information about the test. They responded by saying that all inquiries should go through the Home Office. It is a loop of non-existent evidence. The Home Office rely on ETS. ETS rely on the Home Office. And meanwhile, the early morning raids by immigration officials continue.

Soon after the Home Office trip, immigration minister James Brokenshire went to the Commons and said they had found over 29,000 invalid tests and over 19,000 'questionable test results'. He was not asked any questions about how these numbers had been arrived at.

James Brokenshire told the Commons that 48,000 tests were 'invalid' or'questionable'

Perhaps the tests really did take place and were just as thorough as the Home Office says they were. Perhaps all of those tens of thousands of people are fraudsters. But they deserve to see the evidence upon which they are being judged.

Those accused of fraud have been denied an in-country right of appeal. The only appeal available to them is out-of-country, well after they have been detained and thrown out. In theory the Home Office says those affected can launch a judicial review, but in each individual case it has been denied. A judicial review, they say, would act as a de-facto appeal.

Lawyers believe the Home Office is desperate for none of their claims to be tested in court because the evidence against the students would not be strong enough.

"In cases like these, the burden of proof is on the home secretary," Rehman says. "She has to show, to a high standard of proof, that a particular person sought leave by deception using a fraudulent certificate. Indirect hearsay evidence is nowhere near enough to establish the case to the required standard.

"Many of my clients are well-educated individuals who had obtained qualifications from the UK. Why they would rely on a fraudulent certificate? What is the possible incentive? Nothing."

The test-takers will lose the life they built in the UK and be banned from returning for ten years. Many other countries – certainly any western country – will also refuse them entry on the basis of the decision. And they will have to live with having been branded a liar and a cheat.

This is the new standard of British justice when it comes to immigration.

A Home Office spokesperson said:

"We have taken decisive action against those who have been involved in this extremely serious, large scale, organised fraud of English language tests.

"The American arm of ETS has been analysing English language test results from its test centres in the UK, starting with the highest risk centres. As of June 30th, it had identified more than 29,000 invalid results and 19,000 questionable results. We have used that information to identify those that have used those results to cheat the immigration system.

"We will use all measures available to us to deal with cheaters – including curtailment of leave, removal and entry bans. Individuals who have been caught cheating will have the right to appeal from overseas."