Thousands descended on London to protest on Saturday just days after UK PM Boris Johnson announced he was closing parliament.
The House of Commons will be shut from September 12 to October 14, slashing the time MPs have to block a no-deal Brexit.
Johnson said it was nothing to do with Brexit but critics have slammed the move as a “constitutional outrage”.
It is not unusual for the Queen's speech to be preceded with a suspension of parliament for between five and 20 days, or for parliament to go into recess in mid-September for the conference season.
But critics see the move as a ploy to muffle opposition to a no-deal Brexit in the crucial weeks before October 31.
Other protests were held across the UK, including Cardiff, Edinburgh and Belfast. Outside the country, there were events planned in Berlin, Amsterdam and Copenhagen.