The team debuted on 6 February 2015 in the Chikara promotion. Both Seven and Bate signed with WWE in late 2016 to be a part of the first United Kingdom Championship Tournament, which was won by Bate who became the inaugural WWE United Kingdom Champion. Both wrestlers then joined the NXT brand as singles wrestler, while continuing to team up outside WWE; after Bate lost the title to Dunne in 2017, Moustache Mountain made their debut in WWE the following year, and defeated The Undisputed Era at the NXT U.K. Championship event to win the NXT Tag Team Championship, although they lost it back to The Undisputed Era two days later on "NXT". After signing a full-time contract with WWE, the two, together with Dunne, became central figures of "NXT UK" after its premiere in 2018, unsuccessfully trying to become the inaugural NXT UK Tag Team Champions at .