The Observance of 5th November Act was repealed in 1859.
Passed after the Gunpowder Plot, the 1605 act required an annual thanksgiving service on 5 November. Church ministers were instructed to read the act publicly during prayers, and parishioners were expected to attend. It commemorated the discovery of the plot and the survival of King James I, Parliament and the established government.
The act remained on the statute book for more than 250 years, although its religious and political importance changed over time. The anniversary also acquired an additional royal association after William of Orange landed at Brixham on 5 November 1688 during the Glorious Revolution.
The repeal took effect on 25 March 1859 through the Anniversary Days Observance Act 1859. The year, rather than the day and month, is the usual answer to this question. Repeal ended the statutory requirement for the official church observance, but public Bonfire Night customs continued as popular celebrations.