The 50 pence piece did not officially enter circulation until 1969, but pattern and trial strikes were produced in advance to test the heptagonal design — the first seven-sided coin intended for general British circulation. The Reuleaux heptagon shape was specifically chosen because it rolls at a constant diameter, allowing vending machines to accept it without modification despite its irregular outline.
This 1967 trial predates the decimalization switchover by four years.
The 50 pence piece did not officially enter circulation until 1969, but pattern and trial strikes were produced in advance to test the heptagonal design — the first seven-sided coin intended for general British circulation. The Reuleaux heptagon shape was specifically chosen because it rolls at a constant diameter, allowing vending machines to accept it without modification despite its irregular outline.
This 1967 trial predates the decimalization switchover by four years.