A report from the National Institute of Economic and Social Research last week played down suggestions that local public services would be put under pressure from an influx of Bulgarian and Romanian migrants next year. Jonathan Werran reports on the findings.

Around 10 years ago, during the height of the Gulf War, US defense secretary Donald Rumsfeld memorably ruminated during a press conference about the intelligence available to forces attacking Saddam Hussein's Iraq: 'There are known knowns; there are things we know we know,' Mr Rumsfeld began. 'We also know there are known unknowns; that is to say, we know there are some things we do not know. But there are also unknown unknowns – the ones we don't know we don't know.'