Critics of London Mayor Sadiq Khan on Saturday launched a big balloon caricaturing him in a yellow bikini "in retaliation" for the "Baby Trump" blimp he let fly over Westminster in July.
The stunt was staged by Yanny Bruere, who describes himself as a free speech advocate, and funded through nearly £60,000 ($78,000, 67,000 euros) in donations on a crowdfunding website.
It follows activists flying a giant balloon depicting US President Donald Trump as an orange nappy-clad baby during demonstrations on July 13 against his visit to Britain.
To the fury of Trump supporters, Khan authorised the flying of the caricature, arguing Londoners had a right to peaceful protest.
Bruere, 28, from Northampton, a town 65 miles north of London, confirmed Saturday's launch was to hit back at the mayor.
"I think a certain amount of respect should be afforded to the leader of the free world and the greatest ally the UK has -- the president of America," he said.
Organisers chose the yellow bikini because Khan ruled in 2016 London's transport network would not allow adverts which could create body confidence issues following controversy over a protein shake poster featuring a model in a yellow bikini asking "are you beach body ready?"
A small crowd of supporters and press gathered in Westminster to see the giant inflatable lift off Saturday morning.
It will fly over Parliament Square for two hours.
The mayor said people were welcome to watch the stunt.
"If people want to spend their Saturday looking at me in a yellow bikini they're welcome to do so -- I don't really think yellow's my colour though," he quipped to ITV News.