1 Pound Island of Guernsey Bank

The Island of Guernsey Bank was a private commercial institution, not a Crown or States authority, and its notes had no guaranteed backing beyond the bank's own solvency. Private island banks of this period were notoriously fragile; several Channel Island issuers collapsed within decades of establishment, leaving noteholders with worthless paper. Whether this particular bank survived long enough to redeem its full circulation is worth investigating before attributing significant rarity to any survivor.

Perkins, Bacon & Petch — the firm's name at this precise moment before it became Perkins, Bacon & Co. — used steel intaglio engraving, a technique Jacob Perkins had brought from America specifically to defeat forgery. The dating of the printer's name on any example can itself help narrow the year of printing.