Warwickshire County qualification is by:
a) Birth in the County
b) By 9 months continuous residence in the County prior to the Championship.
c) By 9 months service in a unit of HM Forces stationed in the County.
Warwickshire County is defined as what is currently the County of Warwickshire plus the Metropolitan Boroughs of Coventry, Solihull plus Sutton Coldfield and the parts of Birmingham that used to be in Warwickshire before 1974. To see which parts of Birmingham qualify for Warwickshire see the map linked below. The map is expandable so you can zoom in.
Birmingham in Warwickshire pre-1974