21 ECUs - Elizabeth II Eurotunnel

The ECU — European Currency Unit — was never legal tender in the conventional sense, existing only as a basket currency and accounting unit within the European Monetary System. Gibraltar's enthusiasm for ECU-denominated commemoratives in the early 1990s was partly opportunistic: the territory had no stake in European monetary union yet could freely exploit the ECU's prestige branding. The Channel Tunnel opened in May 1994 after seven years of construction and roughly £4.65 billion in cost overruns that nearly bankrupted Eurotunnel PLC within a year of inauguration.