LONDON — In the annals of British political protest, the giant balloon is the current weapon of choice.

A month ago, protesters hoisted a giant inflatable of President Trump dressed in a diaper and flew it near Parliament — a demonstration given the green light by London’s mayor.

On Saturday morning, a Briton who says the mayor, Sadiq Khan, is not doing enough to fight crime returned the favor and launched a giant balloon of Mr. Khan near Westminster.

The new 29-foot inflatable is the idea of Yanny Bruere, who says he is a free-speech advocate incensed by rising crime. On his crowdfunding page, he wrote: “Under Sadiq Khan, we have seen crime skyrocket to unprecedented levels. People in London don’t feel safe and they aren’t safe, 81 murders this year alone! Khan Out.”