Northern Ireland Independence Referendum.
In 1973, Northern Ireland was asked if they wanted to remain in the UK or join the Republic of Ireland.
57.4% (591,820) of the voting population (1,030,084) voted to “Remain part of the United Kingdom”
Northern Ireland border poll, 1973:
Do you want Northern Ireland to remain part of the United Kingdom?
98.9% voted to Remain part of the United Kingdom
1.1% voted to Join with the Republic of Ireland
10.1 - 560,296