The map extends from the Isle of Sheppey and Faversham to Hearn Bay and is a highly detailed chart of the channels and flats off the coast of Kent. The first issue of this fine large scale sea chart of the River Thames estuary appears to have been in 1786 in Robert Sayer’s ‘Channel Pilot’. This issue is from an edition by Laurie and Whittle who took over Robert Sayer’s business on his death in 1794. John Stephenson is identified in the title as a Master in the Royal Navy. Shirley (2004) M.Say 6a no. 4 (an earlier state).