thornton was made queen's counsel in 1992, and became an editor of the practitioner text "archbold" also in 1992. he was appointed an assistant recorder in 1994, became a recorder on 26 march 1997, and a deputy high court judge in 2003. thornton was appointed a circuit judge on the south eastern circuit on 12 november 2007. in 2011, having been specially appointed assistant deputy coroner, he presided over the inquest into the death of ian tomlinson, who died during protests at the 2009 g20 summit in london. his appointment came after the coroner for the city of london requested that ministers appoint an experienced figure.