Under pressure from Jeremy Paxman on Newsnight in February 2003, Tony Blair conceded that the number of asylum seekers coming to Britain was too high and pledged to halve them by the following September. The promise was widely derided, but Blair had done his homework: officials had assessed the impact of Labour’s 2002 Asylum Act, the closure of the Sangatte asylum centre near Calais and other measures to deter refugees from coming to the UK. When September’s figures were announced, the target had been met.

David Cameron’s target of cutting net migration to ‘tens of thousands’ was first made before the 2010 election, then spelled out – ‘no ifs, no buts’ – in April 2011. A few weeks ago Theresa May called it an ‘objective’ the government was ‘working’ towards. But the nearest they ever got was two years ago, when net migration fell to 154,000. Since then it’s risen to 260,000, higher than when Labour left office. Cameron’s mistake was to assume that net migration to and from the rest of the EU, over which he has little control, would stay where it was in 2011 (under 80,000). The Home Office focused its attention on non-EU migrants – students, family members and skilled workers – all now subject to tighter rules. What Cameron didn’t foresee was that net EU migration would almost double. Or as he put it last week, ‘our squeeze in one area has been offset by a bulge in another.’

So now his aim is to ‘bring down the current spike in numbers’ from the EU. But the measures in his speech on Friday aren’t likely to do it. EU jobseekers, he said, will have to leave after six months if they don’t find a job (but who will make them?). They won’t be eligible for universal credit (but the universal credit scheme is in chaos, and it’s unclear when, if ever, it will be fully implemented). Nationals from countries newly admitted to the EU won’t be allowed into the UK (no new member states are expected soon anyway). Councils won’t let houses to people who have been here less than four years (the tests for getting a council house already prevent most people from getting one that quickly). Children living abroad won’t qualify for tax credits (how many people know their children might be eligible before they come?).

The only measure that might have any bite is preventing migrants from claiming benefits or tax credits until they’ve been here for four years, assuming that it’s legally possible (the government has a track record of flouting EU rules in this area). But the evidence that it will deter people is pretty thin. Rules on who gets benefits have already been tightened in the last two years while immigration from the EU has gone up sharply. The European Commission has shown that few migrants are ‘benefit tourists’ and they depend far less on benefits than the resident population. People either come with a job arranged or expect to get one: if they don’t, a coach ticket back to Warsaw will cost them £70.

From today, a scheme being trialled in the West Midlands will force private landlords to make immigration checks on new tenants. A recent survey showed that four out of five landlords don’t know they’ve got to make the checks. Many of those who do will be strongly tempted to find excuses not to let to anyone who looks like a migrant, because a mistake could cost them a £3000 fine. A year ago undercover BBC reporters found that landlords can easily discriminate against black tenants. The Home Office researchers evaluating the scheme know that it risks making discrimination worse. Cameron says he wants to extend the checks ‘rapidly’, even though the government promised they’d review their impact in the trial area first.

As controls tighten, more migrants will look to landlords who ask no questions because their lettings are illegal anyway. Ealing has about 60,000 people living in ‘beds in sheds’; Slough has 6000 illegal structures; Harrow has more than 300. One landlord in Holloway faces a fine of £280,000, thought to be the biggest ever imposed. But even at this level, landlords with dozens of lettings can take fines in their stride.

The migrants most affected by restrictions on housing and benefits are in the UK already, doing low-paid jobs or – if unemployed – unwilling to ‘go home’. If they lose their job, their marriage breaks down or they get evicted, most try to get their lives back on track like anyone else in today’s insecure economy. Cameron says he’ll ‘reduce the incentives for lower-paid, lower-skilled workers to come to Britain’. What he’ll actually do is make life even more difficult for those already here.