British Coins and Tokens

Elizabeth II (1952-2022), Sterling issues, Pattern Five Pounds, 1966, in silver, by R.G. Hunt and A.M. Foley, conjoined busts of Elizabeth II and the Duke of Edinburgh left, she laureate, rev. Britannia as queen Boadicea, three-quarters left in biga, holding shield and hurling thunderbolt, edge plain, 37.47g/12h (L & S –; ESC 4347). Prooflike, virtually mint state and very rare £1,500-£2,000

See Noble Numismatics Auction 92, lot 3335, for another example (ex Format List 25, no. 3067).
It was suggested in 1966 to the Chancellor of the Exchequer that gold twenty five pound and silver five pound pieces be produced. Foley made a case that these would earn in excess of ten million pounds in foreign currency. Pattern pieces were produced by Hunt and Foley and sent to the Chancellor and the Prime Minister. It is believed that only twenty of these patterns were struck.