Bull is a national personification of Great Britain
similar to the American “Uncle Sam”. He is sometimes used to refer to the whole of the UK, but Scottish and Welsh people do not widely accept him and he is viewed there as English rather than British.John Bull is usually depicted as a stout man in a tailcoat with breeches and a Union Flag waistcoat. He also wears a low topper on his head and is often accompanied by a bulldog.
During the Wars with Napoleon John Bull began to symbolize freedom, loyalty to the king. An average man, so to say, who would fight for his country. Nowadays many British people still view the figure of John Bull as that of honest, generous, outspoken man, ready to stand up for his beliefs.