(Source) When was this document written? What was Halifax’s purpose for writing it?

It was written in 1960.

Explanation:

the best description of postwar writers might be progressive.

following the war, writers showed a tendency to work on artistic or social matters rather than political themes. while postwar literature may not have been the greatest period of english literature, the themes provided excellent critics a high number of novels. such examples include anthony burgess, anthony powell and frank kermode, all of which can be placed under the progressive view.