Allen, along with co-drivers Richard Bradley, Franck Matelli and Gustavo Yacamán drove the #40 Oreca 07 to a 3rd-place finish in the championship.

Allen would switch teams in ELMS 2019 to join DragonSpeed alongside Henrik Hedman, Ben Hanley and Renger van der Zande in the #21 entry.

Allen would return to Graff for the 2020 season, racing the #39 entry alongise Alexandre Cougnaud and Thomas Laurent.

[2] Allen would change teams once again in 2021, joining Panis Racing alongside Julien Canal and Will Stevens.

Allen made his FIA World Endurance Championship debut in 2018 for DragonSpeed at the 6 hours of Fuji.