Born in Wath-upon-Dearne, South Yorkshire, Farnaby trained at the Webber Douglas Academy of Dramatic Art, National Youth Theatre, and Trinity College, Dublin. He was a finalist for the Carlton Hobbes Radio Award and co-devised The Blue Diamond of Azcabar for The Changeling Theatre Company. Simon has played many roles like various characters in Horrible Histories and 'James Blond' in M.I. High. He is also known as 'Farno'.