LONDON — LD50, an art gallery on a quiet street in the shabby-but-hip Dalston section of East London, would seem to be an improbable forum for debates about American politics in the era of President Trump.

But the gallery drew dozens of protesters on Saturday chanting slogans like “Make racists afraid again!” and “No to the Nazis!” The protest was organized in the aftermath of the gallery’s postelection exhibition on the so-called alt-right, the white nationalist movement that has become famous for its online provocations and, critics say, its associations with anti-Semitism, racism and Islamophobia.

The exhibition opened two days after Mr. Trump was elected, and closed in January. It featured printouts of Tweets from far-right groups; engraved statuettes featuring images of Pepe the Frog, a cartoon that has been linked to anti-Semitism; and a diagram tracing the emergence of and connections among online far-right movements.



Public controversy did not boil over, however, until this month, when the London artist Sophie Jung shared on Facebook a message from the gallery’s founder, Lucia Diego, expressing sympathy with what she called President Trump’s “Muslim ban.” The interaction quickly got noticed in London’s large but cliquish art world, and the controversy attracted attention in the tabloids. An expletive along with a hammer-and-sickle symbol and a pink swastika was scrawled outside the gallery, which sits above an architecture firm in a neighborhood dotted with Turkish restaurants and Afro-Caribbean markets.