When Nigel Farage campaigned for a fellow populist, Donald J. Trump, in 2020, he seemed like a faded star seeking the spotlight abroad after it had swung past him at home. Mr. Farage, who helped mobilize the pro-Brexit vote in 2016, was marginalized in Britain, then consumed by the pandemic.
No longer: For three weeks, Mr. Farage, has been back on the front pages of British papers, with an attention-grabbing claim that his exclusive private…