What act was used against the Briton who fired six blank shots at Queen Elizabeth II in 1981?
Treason Act 1842: The Treason Act 1842 (5 & 6 Vict. Treason Act 1842:  It was last used in 1981 to prosecute Marcus Sarjeant. Marcus Sarjeant: Marcus Simon Sarjeant (born 1964) is a Briton who fired six blank shots at Queen Elizabeth II as she rode down The Mall to the Trooping the Colour ceremony in 1981.
Treason Act 1842