David Cameron’s 2010 pre-election pledge to cut immigration by the “tens of thousands” had the unintended, but perhaps inevitable, long-term consequence of stiffening opposition to the European Union within the Conservative Party, and of supercharging the Leave vote in the 2016 EU Referendum.

By putting a figure on his promise, Cameron created a yardstick against which he would be held to account, and which would give Tory-supporting newspapers a ready-made stick with which to beat his government.

Cameron’s target proved to be undeliverable, but he had succeeded in unleashing an unprecedented popular press campaign that would reinforce the link between the Conservative-brand and hostility to immigrants.

Immigration scare stories were already regular newspaper fare and they would become the weapon of choice for the tabloid press during the rise of UKIP, and then the referendum campaign.

The more Nigel Farage thrived on his ability to exploit an anti-immigration platform, the more appealing it subsequently became to leading Conservative Brexiteers who had no hesitation in encouraging and manipulating tabloid headlines warning of the dangers of ineffective controls.

The persuasiveness of this unrelenting campaign was evident across the country. Whenever elderly people were stopped for Vox Pops interviews for television and radio, both during the referendum campaign, and in the long, chaotic aftermath, calls for a curb on immigration were by far and away the most common reason given for having backed Brexit, and that clamour was often the loudest in areas with few if any immigrants.

Older voters’ concerns played to the potency of the Leave slogan “Take Back Control” and their conviction that departure from the EU was the only way the UK could regain control over its borders.

In their post-Brexit analysis, two leading newspapers on either side of the divide were united in their conclusion. The Guardian was in no doubt that it was immigration that had “captured” the Brexit vote; and the Daily Telegraph agreed that immigration was “arguably the driving force behind the Leave majority”.

Perhaps the clearest illustration of Cameron’s folly in committing himself to a target of “tens of thousands” was the misfortune of finding himself backed into a corner when the annual immigration statistics were released less than a month before the referendum vote.

During 2015, overall net immigration had hit a near record of 330,000, of which 270,000 were EU nationals arriving under freedom-of-movement, including 77,000 who had arrived with no job offer.

The Sun’s front page was filled with a mock-up of Cameron’s face with eyes closed and his fingers in his ears, alongside the headline: “As another 333,000 immigrants prove we can’t control our own borders Cameron responds: La-la, la-la, la...”

 Prior to the 2010 general election, the Conservatives had shied away from putting immigration at the centre of the party’s election campaigning, but four months before polling day Cameron had no such inhibitions.

Net immigration was then averaging around 200,000 a year and he declared that a cap was needed:

“We would like to see net immigration in the tens of thousands, rather than the hundreds of thousands. I don’t think that’s unrealistic.” (Andrew Marr Programme, 10.1.2010)

In his final pre-election interview, Cameron told the now defunct News of the World that if Gordon Brown was defeated and he became Prime Minister, a Conservative government would “halve” net immigration.

Calls on the new Prime Minister to honour his pledge were reinforced day after day with headlines in newspapers such as the Sun, Daily Mail and Daily Express blaming migrants for a “surge in crime”; a “rush to get our jobs”; and for the UK’s “foreign baby boom”.

Scare stories worked to the advantage of Nigel Farage in the May 2013 local authority elections and helped deliver a higher than expected vote for UKIP

There was to be no let-up in the press campaign which repeated warnings about the UK having to accommodate a new wave of EU migration from Romania and Bulgaria from the start of 2014.

A Daily Express opinion poll claimed that 98 per cent of those questioned demanded a ban on new migrants.  A Daily Mail opinion survey had 82 per cent against a new influx from Romania and Bulgaria. By December 2013 the Sun was ready to issue an ultimatum to the Prime Minister: “Draw a red line on immigration or else!”

Cameron responded by threatening to veto the admission of new members to the EU unless they accepted tough new control on their citizens moving to the UK. His efforts did little appease his party, or the press, and UKIP were again the beneficiaries in the 2014 elections to the European Parliament, taking a total of 24 seats, ahead of both Labour and the Conservatives.

With the 2015 general election only months away, Cameron ramped up his warnings to the EU: unless Britain was given the right to make European migrants wait four years before receiving welfare payments or council houses, the UK would be prepared to leave the EU.

“I’m ready to lead Britain out of Europe if migrant reforms fail,” said the Daily Telegraph’s banner headline over a report of a speech in which Cameron set out his red lines for continued UK membership.

Against pre-election predictions, Cameron won an outright majority and within months announced that his promised referendum would take place in June 2016, once he had completed fresh negotiations with the EU.

He returned with a new EU settlement that promised a seven-year “emergency brake” on migrant welfare claims, but it was ridiculed by Leave-supporting newspapers: “Cameron’s EU deal is a joke” (Daily Express) and “Call that a deal, Dave?” (Daily Mail).

When the Office for National Statistics confirmed that net migration to the UK had risen to 333,000 in 2015 – the second highest figure on record – the Remain campaign feared the worst.

With less than a month to go, the Daily Mail judged it to be a “hammer blow” to Cameron’s last remaining hopes of pulling off a referendum victory.

Within days the opinion polls were reporting a turnaround in support for Leave. “Migration fears give poll lead to Brexit,” said the I’s front page. Cameron’s fate was sealed.

Illustrations: Sun 27.5.2016; I 1.6.2016