Where a report with respect to a predominantly residential area within their district is submitted to the local housing authority by a person appearing to the authority to be suitably qualified (who may be an officer of the authority), and it appears to the authority, upon consideration of the report and of any other information in their possession—
the authority may cause the area to be defined on a map and by resolution declare it to be a general improvement area.
A general improvement area may not be defined so as to include, but may be defined so as to surround, land which is comprised in a housing action area.
A general improvement area may not (unless the land has been cleared of buildings) be so defined as to include, but may be so defined as to surround—
and where the Secretary of State on confirming a compulsory purchase order under Schedule 22 (acquisition of land for clearance) modifies the order by excluding from a clearance area land adjoining a general improvement area, the land shall, unless the Secretary of State otherwise directs, be taken to be included in the general improvement area.