When it comes to immigration the same standards of proof apply everywhere, as do the same processes of reverse-engineering. For its 2000 report into migration the British government went to two of the academics most noted for their views in favour of mass immigration – Sarah Spencer and Jonathan Portes – to find justifications for the policies that politicians like Barbara Roche wanted to pursue. For such work the usual standards of academic rigour did not apply. Wherever a claim was desirable, ‘evidence’ was found to support it. Wherever a situation existed that was deemed undesirable, there was said to be either ‘no evidence’ or merely ‘anecdotal evidence’. There was, for instance, only ‘anecdotal evidence’ that ‘high concentrations of migrant children lacking English as a first language can lead to pressure on schools’ and to ‘some concern among other parents’. Not only ‘anecdotal’, but an anecdote heard only from ‘some’. It also explained that it was only ‘in theory’ that mass immigration ‘may increase pressure on housing markets, transport and other infrastructure and exacerbate over-crowding and congestion’. The reality, it aimed to suggest, was wholly different. How could anyone imagine that an influx of more people would require more houses?

These were hardly surprising findings from authors with a track record of being in favour of mass migration as a good in itself. But while their work presented itself as an economic analysis of the benefits of migration, it was in fact not just a blueprint for societal change but a cheerleader for it. In arguing the case for mass immigration the authors insisted that migrant children would bring ‘greater diversity into UK schools’. All potential concerns for British workers were similarly swept aside. There was, for instance, ‘little evidence that native workers are harmed’ by large-scale immigration. In fact, ‘Migrants will have no effect on the job prospects of natives.’

The insertion of figures such as Spencer and Portes from the fringes of academia into Whitehall gave their opinions not only the veneer of respectability but the stamp of government. After publication of their report, ministers like Roche had something to point to when they insisted that mass migration brought unadulterated economic benefits. And if anybody wonders how the Labour government let immigration run away so wildly under its watch, it is in part because of the oiling effect of work like this.