There was a one hour period before failing to have dispersed was an offense, but that wouldn't necessarily have stopped troops (legally) opening fire if they were being charged.
"Lord Mansfield observed that the Riot Act did not take away the pre-existing power of the authorities to use force to stop a violent riot." (But the context was that he was clearing up confusion after riots where that was unclear, so it might well have discouraged use of force during that hour.) http://en.wikipedia.org/wiki/Riot_Act#Subsequent_history_of_the_Riot_Act_in_the_UK
no subject
Date: 2012-01-29 11:00 am (UTC)"Lord Mansfield observed that the Riot Act did not take away the pre-existing power of the authorities to use force to stop a violent riot." (But the context was that he was clearing up confusion after riots where that was unclear, so it might well have discouraged use of force during that hour.)
http://en.wikipedia.org/wiki/Riot_Act#Subsequent_history_of_the_Riot_Act_in_the_UK