Theresa May cut an isolated figure pandering to the Ukip vote – but her speech summed up Tory sentiment

You've got to feel sorry for Theresa May. She clearly didn't get the Tories' pre-Conference memo. While everyone else was falling over themselves to join in the sudden revival of compassionate Conservatism, she was still pandering to the UKIP vote.

Or maybe she did get the memo but, for reasons of post-Cameron positioning, choose to ignore it. Either way, her speech struck a discordant, unpleasant note and the Home Secretary cut an isolated figure amidst all the back-slapping in Manchester.

But, to be fair, her speech was probably the most honest of the week. It was an accurate echo of the right-wing sentiment that informed the Tory manifesto and the subsequent Queen's Speech.

This week, one of the flagship Bills in that speech - the Immigration Bill - will be debated in the Commons. It is the legislative equivalent of the Home Secretary's address to her Party faithful in Manchester: disproportionate, divisive, deceitful. It seeks to propagate immigration myths rather than slay them and, like her speech, owes more to headline-chasing rhetoric rather than clear, hard evidence.

The Home Secretary has presented a raft of initiatives to the Commons since 2010. Net migration has risen to record levels in that time and there is no evidence at all to suggest that this Bill will do anything to reduce immigration.

It also presents the Government with a big PR headache. How can they make it match the new, centrist tone struck by the Prime Minister in Manchester and prevent it looking like a return of the Nasty Party?

The Prime Minister's speech marked a welcome departure from his recent rhetoric. Gone was any dog-whistle talk of "swarms" of refugees. Instead, it included an undeniably powerful passage about young people from black or Asian backgrounds sending out CVs only to be greeted with repeated rejection.

David Cameron was absolutely right to raise this hidden issue and to say that such casual discrimination has no place in 21st Century Britain. But his decision to do so raises a tricky question for him: if he truly believes what he was saying, why on earth is he about to legislate to make the same everyday racism far more likely to happen in the housing market?

The aim of the Immigration Bill is to make Britain a "hostile environment" for illegal migrants. In practice, it could end up making Britain a more hostile place for anyone with a foreign-sounding name - worsening the very problem that Cameron said he wanted to challenge.

At the heart of the Bill is 'Right to Rent' - a new scheme to make private landlords check the immigration status of new tenants. If they fail to do so, they could be fined or even sent to jail.

The Tories first tried to introduce this towards the end of the last Parliament, but were forced to pilot it first across the West Midlands. The results are alarming. A study by the Joint Council for the Welfare of Immigrants found that 42% of landlords said the Right to Rent scheme made them less likely to rent a property to someone who does not have a British passport; 27% said they were now reluctant even to engage with those with foreign names or accents.

On this evidence, 'Right to Rent' in its current form could lead to widespread discrimination. Of course, we have come a long way as a society since landlords displayed unwelcoming notices in their windows. But the new document checks could become the modern equivalent of the "no dogs, no blacks, no Irish" signs and, by being more insidious, such casual discrimination will be far harder to challenge.

It is surely an unprecedented situation for a British Prime Minister to be poised to pass legislation that will accentuate a problem he was railing against just days before in his Conference speech. For that reason, I urge him to overrule his Home Secretary and drop these plans. If he proceeds with them, it will confirm a suspicion about Cameron of as shallow man who says things in the moment out of convenience rather than conviction.

A much better approach on immigration would be if Cameron worked with Labour to find the "common ground" he spoke of in Manchester.

There is, of course, an important debate to be had about the impact of immigration. If politicians fail to have it, it leaves a vacuum and allows myths to be created. That in turn leads to a risk of over-compensation and politicians trying to catch up by legislating for headlines and pandering to prejudice. This is the trap that the Home Secretary and her Immigration Bill have fallen into. But this is not a Westminster game: in this policy area, unlike others, the very tone of the political debate can cause harm and strife in the real world.

That is why it is essential to proceed with caution and on the basis of the evidence. I strongly disagree with the Home Secretary's claim that the economic benefits of immigration have been "close to zero". As the CBI and IOD rightly pointed out, all the evidence suggests it has been net beneficial. And the sadness is, by opting for rhetoric over reason, the Home Secretary distracted attention from a neglected issue which she was right to raise: the effects of EU migration on the poorest communities and people on the lowest wages.

What business leaders and politicians who talk of the overall net benefit of immigration often fail to acknowledge is that it has had a differential impact on different places. It may have helped boost growth in the big cities but, in former industrial areas, a free, unregulated or black market in labour can lead to a race-to-bottom and end up benefiting companies more than people.

This is why I said in my own Party Conference speech that the time has come for Labour to reframe the debate about immigration. For too long, the Left has failed to acknowledge the fact that EU free movement on the current rules, and the free market in labour it creates, can under-cut wages and widen inequality. Our failure to talk about these issues has left us looking out of touch to voters in our own heartlands.

If politicians truly want to find "common ground" on immigration, let's ditch the rhetoric. Instead, let's focus on finding practical answers that deal with its real effects on people's lives. For instance, I have called for new EU rules to protect the "going rate" of the skilled workforce as one of Britain's renegotiation demands. I hope the Home Secretary will join forces with me on it. It is surely a much better approach to start from a positive position of supporting free movement but requiring it to be underpinned by stronger rules to make it work for everyone.

As we saw with the reaction to Theresa May's speech, the public can spot a politician playing politics with this issue a million miles away. I don't believe the vast majority of British people have any problem with people coming here to work and contribute to our economy and society. Nor do they want Britain turned into a "hostile" country. They just want a sense of fairness and rules to achieve it.

As Labour's motion on Tuesday will make clear, we are prepared to support the Government where it has proportionate proposals to tackle illegal immigration, strengthen our borders and stop the exploitation of migrants by unscrupulous employers and landlords. But what we will never be prepared to do is let the Government pander to prejudice and legislate in haste to entrench the kind of casual discrimination which the Prime Minister claims to oppose.

In her own Conference speech, the Home Secretary claimed immigration was undermining social cohesion. The truth is that knee-jerk, divisive measures of the kind we see in her Immigration Bill are far more likely to do that. That is why, on Tuesday, I will be calling on the Home Secretary to think again and asking my colleagues to oppose her Bill.

Andy Burnham is the shadow Home Secretary