Theory made his Progress Wrestling debut in 2017 at a Progress and Evolve joint show, where him, Jason Kincaid and Blaster McMassive were defeated by Keith Lee.[27] In August 2017, Theory, Mark Andrews and Lee were defeated by Mark Haskins.[28] At Chapter 67, Theory and Jinny defeated Will Ospreay and Kay Lee Ray.[29] On 12 December, Progress announced that Theory would be making his United Kingdom debut and compete at Chapter 85: Progro.naut and Chapter 86: Corrupted Harmony on 9 and 10 March, respectively.