Government of Gibraltar, watermarked paper featuring a repeated key motif, as used on all ‘Rock of Gibraltar’ notes from 1927 until 1975, this watermark was in continuous use for 47 years, although this is a later (1954-75) example with security thread, glued into blue card frame, ink annotations on paper, as produced, the only example of any Gibraltar watermarked paper in the entire Portals archive, extremely rare
BNB B112-B117, Pick 11-19 for types £150-£200

These items are directly from the Portals Paper archive