The protest is organised by the activist group Take Back Democracy, who describe themselves as “entirely fed up with the UK government of Boris Johnson and the Tory party”.
A statement on their website reads: “We felt compelled to do something in the wake of the ongoing corruption of the UK Government. We wanted to do something to stop the slide into fascism and to be a counterargument to the populist agenda.
“We believe in inclusion, equality, and a fair country for everyone. We have no party-political affiliations, and we are members of different parties and no parties.”
The Undoing actor Grant, who has been a vocal critic of the Conservative party for years, shared a tweet by one of the group’s activists, who has the Twitter handle @NoMoreGreed, saying: “Never have I seen more businesses going bust, more people in poverty, such a great divide between rich and poor, or such corruption in our government.
“It has to change and it starts Saturday.”
Grant shared the post with a pointing finger and a fist emoji.
Last year, Grant accused the government of using the Covid-19 pandemic as an opportunity to “enrich” its friends and donors.
And in January, the actor hit out at the government over plans to scrap the licence fee that funds the BBC, calling politicians “spittle-flecked nut jobs” who “want to destroy” the corporation.
Johnson has recently come under fire for parties held in Downing Street during the height of the lockdown.
His goverment has also been accused of “plunging people into poverty” by Labour’s deputy leader Angela Rayner, who claimed earlier this month that Tory politicians are failing to get a grip on cost-of-living issues affecting working families.
The protest against Johnson starts at midday on Parliament Square in London on Saturday 19 February.