at that time), there was an ever-increasing demand for a mail system that would serve London and its suburbs. With its cheap flat postage-rate of one penny, the Penny Post quickly became a commercial success. Premier postal system Several Penny Post offices were established at various points within London where letters that were collected from drop-boxes about the city were sorted and sent out for delivery. Dockwra, Murrey and their partners divided London as far as (inclusively) Westminster and Blackwall and Hackney and Lambeth into seven districts with a sorting office for each. They established a Head Office that was set up in the home of Dockwra himself who was living in a mansion on Lime Street that was formerly owned by Sir Robert Abdy. Dockwra established hourly collections, with a maximum of ten deliveries daily for London and a minimum of six deliveries for the various London suburbs, such as Hackney and Islington. However Robert Murray was arrested in May 1680, along with another associate of the Penny Post, George Cowdron, for distributing by means of the Penny Post what was considered to be seditious material criticising the Duke of York (afterwards James II). This left Dockwra to manage the Penny Post and as such credit is roundly given to him for its designs and further improvements as the Penny Post at that point having only been in operation for a couple of months was still in its developmental stages. Within two years the Penny Post had grown to such proportions that approximately four to five hundred receiving-houses and wall-boxes had been established at various locations about the city of London, however some of the accounts vary. E.g. in Robert Seymour's Survey of London and Westminster, published in 1735, he puts the number of receiving houses at over 600. Dockwra's Penny Post delivered letters and packets weighing up to one pound and delivery was guaranteed within four hours, each letter being marked with a heart shaped time stamp indicating the time an item was dropped off for delivery. Because the new postal service was affordable to the general public with its inexpensive flat rate of one penny it became an almost instant success and became the predecessor of the postal systems that later emerged and are still in use today in Great Britain and elsewhere today. To announce the new Penny Post's inter-city mail services public notices were published