The Home Office, under Theresa May, was aware of significant concerns about the potential for hostile environment measures to result in discrimination, the review finds. It adds: "Despite the warnings, the department failed to monitor, or properly evaluate, the effectiveness and impact of the compliant environment measures."
the review makes it clear that the roots of the scandal stretch back over the decades, as immigration legislation was gradually tightened from 1948 onwards, including by Labour governments in the 1990's.
However, it pinpoints the development of hostile environment policies during Theresa May's time at the Home office as the moment at which problems escalated.
A key failure was a misplaced assumption in the impact assessments for the 2013 and 2015 immigration bills that those who were unable to prove they were here legally, were therefore here unlawfully. Around 17% of the UK population do not have passports, and until the introduction of the hostile environment, most people have not needed them.
Following the report's publication, Labour called for a repeal of the hostile environment legislation, but the Home Secretary, Priti Patel, only said she would review the reports recommendations.
Williams found a consistent desire among civil servants, and Ministers, to blame Windrushers for their own plight.
Some Windrush victims remain in severe financial and personal difficulties, facing homelessness and unemployment because of Home Office policies. Many people affected have not approached the Home Office because they are scared of the threat of immigration enforcement action, Williams notes.
The true scale of the scandal remains unknown.