I'm afraid I cannot throw any light on 'Swann'.
Out of interest how much do you know of his navy service? I ask because I'm particularly interested in CG men who served in the RN during the Crimean War, and Frederick was one such man, serving on HMS Belleisle in the Baltic. At the outbreak of war he was serving on the Revenue Cruiser Dolphin, returning to her when his navy service ended. It was from this boat that he was nominated to the land-based CG service in 1858.
Martin