Campaign group 38 Degrees has projected a stark message onto the Houses of Parliament and Tower Bridge: "Democracy is not for sale."
The message, aimed at Donald Trump adviser Elon Musk and British politicians, comes as Mr Musk distributed US$1 million (£780,000) to voters in the state of Wisconsin.
The light projection included green and pink lettering and animations of American bills with Mr Musk’s face on them.
The demonstration highlights 38 Degrees' campaign urging the government to close legal loopholes that it says could allow foreign billionaires to exert undue influence on British politics.
