A man was detained on Wednesday after an egg was thrown at King Charles and his wife Queen Camilla as they carried out an engagement in northern England, according to a Reuters witness.
Police moved in to arrest the man who was in the crowd as the royal couple arrived for a ceremony in York.
Local media reported that the man shouted that Britain was "built on the blood of slavery" before being apprehended by police.
He was also booed by the crowd that had gathered to see the king and queen consort.
The crowd also shouted "shame on you" and "God save the King", according to reports.
