Brexit risks creating an "undercutting free-for-all" in the British economy. That’s the key finding of our new report, Brexit and Immigration: Prioritising the Rights of All Workers. It should alarm all Labour members and supporters. Motions on Brexit and free movement may not have been heard, but as the party meets in Brighton we must remember that migrant workers with less rights will be more vulnerable to super exploitation. Creating a second-class migrant workforce risks compounding the insecurities that all workers face in Britain.

The system of free movement is poorly understood. It provides EU citizens with a series of conditional rights they have when living in other EU countries, particularly the right to work and study. EU citizens activating these "treaty rights" cannot be discriminated against in the labour market and should not be treated differently by employers on the grounds of their nationality.

Unfortunately, workers’ rights in the UK often only observe minimum EU standards. Trade unions face some of the most restrictive laws of any democracy in the world. Decades of outsourcing and the creation of hyper "flexible" labour markets - most recently in the so-called "gig economy" - have played workers off against one another. Pyramids of outsourced operations, with companies competing over delivering the work for the lowest price, have pushed down the pay and conditions in many sectors.

These changes are all too often associated with migration. But they arise from a lack of robust workers’ rights, combined with a broken free market economic model.

When post-Brexit immigration policy is discussed, employer sponsorship of visas and the use of time-limited work permits are repeatedly raised. In fact, there is an unused visa category of the points-based system the UK government uses for non-EEA (European Economic Area) workers, which already contains these provisions. On this suspended visa category, workers can only come into the country under the sponsorship of a vetted employer or agent, and have no right to move work once they arrive. The employer is responsible for their accommodation and for ensuring they are returned to their home country when the visa expires. These conditions may well be in breach of the "right to a free choice of employment" protected in the United Nations Declaration of Human Rights and are in any case a recipe for a second-class migrant workforce suffering super-exploitation.

We show in the report how these types of visa system have a terrible track record. They empower unscrupulous employers and drive down pay and conditions. The ultimate logic is the appalling conditions faced by workers building the football stadiums for the Qatar World Cup. There, a lack of political rights gives extraordinary powers to contractors (the confiscation of passports and the denial of "exit permits" for those seeking their old life are the norm). In the UK, workers coming into the country on the Domestic Workers in a Private Household Visa are also hugely dependent on their sponsors - and the result can be exploitation and slavery.

Britain is now at risk of creating a "worst of both worlds" system: an already poorly regulated, exploitative labour market combined with reducing the rights of migrant workers to such a degree that it would inevitably force down conditions faced by all.

The alternative to these bad choices already exists. It's called free movement+ (the plus refers to a new deal prioritising the rights of all workers). The aim is to improve the rights of workers whatever their nationality. By establishing a legal position for trade union negotiated agreements in key sectors, prioritising those with large numbers of migrant and low paid workers, we can ensure a minimum rate for the job is upheld no matter where the worker has come from. Raising the minimum wage, banning zero hours contracts, establishing a minister of labour to reign in unscrupulous employers, could also form part of this new agenda. Many of these ideas are already in Labour’s dramatically popular 2017 election manifesto. As Tory Brexit lurches from crisis to crisis now is the time for the party to adopt a bold new approach. Free movement+ is the only way to prioritise the rights of all workers.