The Belize Act 1981 (1981 c. 52) was an Act of Parliament in the United Kingdom. It came into operation on July 28, 1981.
The Act made provisions for the nation of Belize (formerly British Honduras) to gain full independence and become a member of the Commonwealth of Nations as a Commonwealth realm; prior to this, Belize had been a fully self-governing British colony from 1973.
Belize became independent on September 21, 1981.
References
Belize Act 1981 Wikipedia(Text) CC BY-SA