There are so many aspects of what has become known as the Windrush affair it is hard to know where to start when drawing lessons. In the end it played a key role in the process that led to the resignation of the home secretary. But there are other more durable lessons to be learned.

The policy which led to many people being unable to stay in their jobs or even being deported despite their apparent right to do so, was a result of a severe tightening of the screw on illegal immigrants.