Simmerson first appears in "Sharpe's Eagle", as commanding officer of the South Essex Regiment of the British Army, during the Talavera Campaign. Captain Michael Hogan briefly sketches Simmerson's background as a Justice of the Peace, Member of Parliament for Paglesham, (a rotten borough), and a colonel in the Militia. He is also a distant cousin of General Sir Banastre Tarleton and thus has some influence at Horse Guards which serves to protect him, to a considerable extent, from the full consequences of his cowardice and military ineptitude. His considerable (inherited) wealth has allowed him to not only purchase his commission in the army, but also raise the regiment at his own expense.