By the standards of a guerrilla artform with unlikely roots in Cool Britannia, the latest example was modest, if direct. On Tuesday night, an activist group in San Francisco projected a brief message on to the walls of Twitter’s headquarters: “@jack is #complicit”.

As photos of the projection went viral (on Twitter, naturally), Resistance SF explained on its Facebook page that it was accusing Twitter co-founder and CEO Jack Dorsey of “amplifying a madman” and “endangering the world” by maintaining a platform for Donald Trump.

The message came three hours after the US president had boasted about the size of his nuclear button in response to claims about the position of Kim Jong-un’s nuclear button (Kim said his button is on his desk, but Trump said his button was “much bigger”). In a second projection, the group followed up with “Ban @realDonaldTrump”.

Merkel protest on the German embassy in London, 2015. Photograph: Jubilee Debt Campaign/Global Justice Now

It was the latest use of “projection bombing”, a technique pioneered by marketing agencies and more recently embraced by campaign groups. In Britain, government buildings are routinely bathed in slogans following a simple – and affordable – formula: knock up an image, get a projector and a decent battery, flick the switch until the cops move you on. Oh, and don’t forget to alert a news photographer.

“It’s a great way to get out a message that’s not being heard inside a building, but has grassroots support,” says Nick Dearden, a veteran projection bomber and director of London-based campaigners Global Justice Now. “Media come to us when an issue is emerging, but when it gets high up the news agenda, we get drowned out because political parties get involved. So this is one way to get coverage, but it’s also something people can share on social media.”

In 2015, Dearden helped organise the projection of Angela Merkel’s image on to the German embassy in London with the words “CANCEL GREEK DEBT”, in a protest by another group, the Jubilee Debt Campaign. On that occasion, they recruited a company that creates projection adverts and paid “a couple of grand” for the work. The projector sat beside the sliding door of a van.

The message writ large on Dover’s cliffs before a far-right rally, 2016. Photograph: Jess Hurd/Global Justice Now

A year later, Dearden recruited an anonymous guerrilla projector operator who had contacted him. They threw “#REFUGEES WELCOME” on to the white cliffs of Dover just before a far-right rally in the town. Using a standard, powerful projector and some smart software to prevent distortion, the man set up a tripod on the beach below the cliffs.

Last year, the same man turned up at Britain’s most popular projection bombsite; halfway along Westminster Bridge, he projected the words, “Say no to Trump” on to the Houses of Parliament, the day before MPs debated the president’s proposed state visit. “We were really nervous about the police, but it looked like we were just taking pictures,” Dearden recalls.

The image of a nude Gail Porter on the Houses of Parliament put projection on the map in 1999. Photograph: Michael Walter/PA

The law is blurry when it comes to projection, but local authorities and building owners can demand permission or take action against unauthorised stunts. Parliamentary projections have become so popular that in 2016 the House of Commons complained that they were detracting from authorised images, including a vast photo of Usain Bolt displayed during the 2012 Olympics.

Dearden says he was inspired by the projection of “No War On Iraq” on to the Houses of Parliament in 2002, but all such stunts owe a debt to Anna Carloss. Late on a Sunday night in May 1999, she and her new marketing agency, Cunning, put together a crew to project a nude photo of Gail Porter on to the seat of government. The image, conceived to promote FHM’s poll to find the world’s 100 sexiest women, went globally viral in the predigital, lads’ mag age.

The kit was bigger then and the team had to park a van on the bridge – an impossible feat today. “It was a good 10 minutes before the police came up, but they were highly amused,” Carloss recalls, 18 years later. “We actually came back on the Monday night with a revised image, but that time we were asked to move on pretty quickly, because Betty Boothroyd was in her Speaker’s offices and we were shining a bright light into it.” Carloss can’t recall which part of Porter beamed into Boothroyd’s quarters.

“It definitely put projection on the map. It was just a perfect zeitgeist moment that I don’t think any projection has achieved since,” Carloss says from her office at Cunning, which flourished after its triumph. “We’ve had to manage client expectations since and steer them on to other ideas.” In the meantime, activists have made the artform their own.