5 Pounds - Elizabeth II Decimalisation, Silver proof

Issued to mark the fiftieth anniversary of British decimal currency, introduced on 15 February 1971 — a date the Treasury had been working toward since the Halsbury Committee recommended decimalisation in 1963. The eight-year lead time was considered the minimum needed to retool vending machines, reprinting price lists, and retrain a public deeply accustomed to 240 pence to the pound.

Guernsey had its own wrinkle: the Bailiwick had operated a distinct local coinage for centuries and used the transition as an opportunity to consolidate under a fully metricated series, quietly retiring several denominations with no equivalent in the new system.