Complex sentence: He remembers having to hide under a window or chair when the council man came to collect the rent; after knocking, the rent man would walk round the house peering through the windows to see whether anyone was at home.
Split into simpler sentences: He remembers having to hide under a window or chair when the council man came to collect the rent. After knocking, the rent man would walk round the house peering through the windows to see whether anyone was at home.