As befits a secret society, almost nothing is known of the Gehagan Society today. It appears to have claimed great antiquity, claiming an origin in the time of St. Polycarp (69-155 AD). It was probably one of many secret societies which emerged in the early to mid-19th century in London and elsewhere. 

This piece is particularly interesting as although it is hallmarked London 1806, the engraving is in part over the hallmarks, suggesting a later date. It is possible that the hallmarks originally belonged to this pass, and that it was re-engraved when worn out, suggesting that the society lasted many years. Alternatively, it is possible that the pass is as late as e.g. the 1840s, and was produced from an old article of silverware. The style of the engraving strongly supports a date before circa 1850 although it is possible that a later engraver imitated an antique style. 

VF or better, pierced with original silver loop. Extremely rare, very few examples known. 

BNJ vol. 20 (1929), p. 300 mentions a similar or the same badge.