Complex sentence: While working as a bricklayer, he began to be educated in Marxism and socialism by fellow workers who lent him books, and he became more politicised after being sacked from a site for joining a trade union.
Split into simpler sentences: While working as a bricklayer, he began to be educated in Marxism and socialism by fellow workers who lent him books. He became more politicised after being sacked from a site for joining a trade union.