Complex sentence: There were several Penny Post offices in London where letters were collected from drop-boxes about the city and sorted for delivery, one of them situated in the home of Dockwra who was living in a mansion on Lime Street, formerly owned by Sir Robert Abdy.
Split into simpler sentences: There were several Penny Post offices in London where letters were collected from drop-boxes about the city and sorted for delivery. One of the offices wwas situated in the home of Dockwra who was living in a mansion on Lime Street, formerly owned by Sir Robert Abdy.