Until the early 1970s, UK immigration rules did not include a category of ‘illegal’ immigration. This chapter traces the shift from this largely permissive immigration regime based on the use of caps and criteria, to the more individualised approach based on illegalisation and individual punishment that emerged in the late 1960s and early 1970s. It shows how this new, individualised approach was considered by officials and the Labour government as a necessary response to political expectations, rather than a means of better steering migration. The individualised approach also necessitated - and enabled - new forms of state knowledge of irregular migrants. However, a lack of operational commitment to this approach led to relatively lax implementation, and a residual issue of limited state knowledge of unauthorised migrants.

In our concluding chapter, we review the evolution of state infrastructures of control. Such infrastructures embody state beliefs about how best to steer migrants, and also provide maps with which states ‘see’ their unauthorised populations. We chart changes in infrastructures since the 1960s across three dimensions: styles, sites and temporalities of control. The analysis highlights the continued reliance on centralised command and control approaches in Germany, despite niggling concerns that they are not capturing the full picture. In France, patchy implementation of work and welfare restrictions, and a sharp left-right divide on the issue, has repeatedly led governments back to the tool of regularisation. In the UK, lack of internal control infrastructure has been compensated for by outsourcing to external organisations, meaning that migrants get ‘caught’ at later stages in their lives when they are most reliant on social and economic support. We explore the implications of these different infrastructures on state knowledge and ignorance.