Saint Helena 1925 Official Envelope Handstamped "The Castle"

1925 OHMS stationery envelope adressed to Canada and bearing strikes of cds NO 16 (type CDS4), Official handstamp "THE CASTLE" 16 NOV (in a format not recorded by Hibbert - a combination of sans-serif and serif capitals in a single lined outer oval), in violet and the boxed OFFICIAL PAID handstamp (type OFF5). Attractive cover illustrative of these scarce postmarks. F-VF.