A British anti-immigration activist has pleaded guilty to slashing a migrant dinghy in the English Channel while a rescuer was aboard. The 37-year-old Daniel Thomas admitted to criminal damage at a hearing in Portsmouth Crown Court on Thursday. The incident happened Sept. 22 when Thomas used a knife on an inflatable boat. The boat was empty of migrants but had a French rescue services member aboard. Thomas is the founder of the Patriot Platform group. He has led protests against migrants crossing the English Channel. These protests have often turned confrontational, with large groups clashing with police. The U.K. government has condemned the behavior of anti-immigrant demonstrators.