Seppings began his career as a naval architect at Plymouth where he was apprenticed as a working shipwright in 1782. By the end of the century he had become the Master Shipwright assistant there, and in 1800 came to the Admiralty’s notice by inventing a new lifting device for ships in drydock. This, with the encouragement given him by John Henslow, the Surveyor, resulted in him becoming Master Shipwright at Chatham in 1804. His experiments with diagonal stressing in the construction of ships led to his appointment as Surveyor to the Navy in 1813, a position he held until 1835.

William Bradley was born in Manchester, and first worked as an errand boy before setting up as a portrait painter there He moved to London in 1823 where he was encouraged by Thomas Lawrence and had success with the industrial middle classes.