20 Company Rupees Union Bank, Calcutta

The Union Bank of Calcutta was one of the three "presidency banks" era private joint-stock banks operating in British India during the mid-nineteenth century, though unlike the Bank of Bengal it lacked government backing and eventually collapsed in 1848 — just one year after this note was issued — in a spectacular failure that wiped out shareholders and depositors alike. The bank's insolvency was part of a broader credit crisis that had been building since the speculative boom of the early 1840s.

A surviving 1847 note predates the collapse by months. Given that failed-bank paper was rarely preserved systematically in colonial India, examples from this issuer are genuinely uncommon in any condition.