Forsyth has reinterpretted a number of Pictish Ogham stone inscriptions that were previously thought to be written in an unknown pre-Indo-European language, and has argued that the Picts spoke a Brythonic language.
Forsyth reinterpretou varias inscricións pictas en ogham que se pensaban que estaban escritas nunha lingua preindoeuropea descoñecida, e defendeu que os pictos falaban unha lingua britónica.