‘The aim is to create here in Britain a really hostile environment for illegal migration’: Theresa May, then Home Secretary. The term was used in an interview by Mrs May in 2012.

A ‘Hostile Environment’ can be defined as an environment (in this case one relating to immigration services, such as settlement and leave to remain [LTR]) in which certain categories of individuals, and certain actions [such as seeking entry to, and/or legal basis settlement in the UK, are deterred, by mechanisms and procedures through existing and/or new, legal statutes and administrative processes. 

Please read the History page — http://needtoknow-immigrationuk.com/history/ — of this section of the website, for more detail on the actual origins and subsequent implementation progression of the Hostile Environment as an introduction to the latter (this online information resource providing fuller applied operational level detail on the full scale of that implementation progresion).