LONDON (AP) — On his way to be crowned this week, King Charles III will travel by gilded coach through streets swathed in red, white and blue Union flags — and past a warning from history.

At Trafalgar Square stands a large bronze statue of King Charles I, the 17th-century monarch deposed by Parliament and executed in 1649. On Saturday, more than 1,500 protesters, dressed in yellow for maximum visibility, plan to gather beside it to chant “Not my king” as the royal procession goes by.

“We’ll try and keep the atmosphere light, but our aim is to make it impossible to ignore,” said Graham Smith, chief executive of the anti-monarchist group Republic.

The coronation, he said, is “a celebration of a corrupt institution. And it is a celebration of one man taking a job that he has not earned.”

Republican activists have long struggled to build momentum to dislodge Britain’s 1,000-year-old monarchy. But they see the coronation as a moment of opportunity.

Queen Elizabeth II, who died in September after 70 years on the throne, was widely respected because of her longevity and sense of duty. Charles is another matter, a 74-year-old whose family feuds and firm opinions on everything from architecture to the environment have been headline fodder for decades.

Opinion polls suggest opposition and apathy to the monarchy are both growing. In a recent study by the National Center for Social Research, just 29 per cent of respondents thought the monarchy was “very important” – the lowest level in the centre’s 40 years of research on the subject. Opposition was highest among the young.

“I think it’s definitely shifting,” said Smith, whose group wants to replace the monarch with an elected head of state. “People are quite happy to criticise Charles in a way they weren’t willing to necessarily in public about the queen.”

Millions in Britain will watch broadcasts when Charles is crowned in Westminster Abbey. Tens of thousands will line the streets, and neighbourhoods across the country will hold parties.

But millions more will ignore the ceremonies. Some will attend alternative events, including a gig in Glasgow by tribute band the Scottish Sex Pistols, recapturing the spirit of punks who sang “God save the queen, the fascist regime” during the late queen’s 1977 silver jubilee.

London’s Newington Green Meeting House, a gathering place for religious dissenters and radicals for 300 years, is holding an “alternative community party,” complete with food, drink and “radical and republican” music.