Dickinson served as Lord Mayor between in the year from 1756 which fell at the same time as the loss of Minorca. Under him the City address presented by mainly Tory aldermen including Ladbroke and Dickinson to King George II asked for 'the authors of our late losses and disappointments to be inquired and punished' which the King informed the city would be the case. In March 1757 at the time of Admiral John Byng's trial and execution a handful of Tory aldermen attempted to gain Dickinson's support for a petition to spare Byng's life, which the Lord Mayor considered to be too late. Byng was executed less than a week later.