Complex sentence: He was honorary president of the National Union of Police and Prison Officers which existed between 1913 and 1918: the police strikes in 1918 and 1919 resulted in the Police Act 1919 which resulted police being banned from joining a trade union and from striking.
Split into simpler sentences: He was honorary president of the National Union of Police and Prison Officers which existed between 1913 and 1918. The police strikes in 1918 and 1919 resulted in the Police Act 1919 which banned police from joining a trade union and from striking.