If you Read The Riot Act to an individual or group of people you are giving him/her or them a severe ticking off about their bad behaviour. The original Riot Act was passed in 1715 by the British government to increase the powers of the civil authorities when a town was threatened by riotous behaviour. The Act read: “Our Sovereign Lord the King chargeth and commandeth all persons being assembled immediately to disperse themselves, and peaceably to depart to their habitations or to their lawful business, upon the pains contained in the Act made in the first year of King George for preventing tumultuous and riotous assemblies. God save the King.”

The Riot Act made it a serious crime for groups of 12 or more not to disperse within one hour of the act being read out to the mob. People failing to disperse risked penal servitude for three years or more or imprisonment with hard labour for up to two years. Reading it out often took great courage and often, during serious disturbances, many didn't even hear it. Many convicted demonstrators, after the infamous Peterloo Massacre near Manchester in 1819, claimed not to have heard it being read out. The same defence was used during trials for the 1743 Gin Riots, 1768 St George's Massacre and the 1780 Gordon Riots. The Act was on the statute book until the 1970s, though little use had been made of it for over a century.