Mowlem became a well-known name in Britcar, after racing with FF Corse in Ferraris with Welsh driver Bonamy Grimes, in 2016 he claimed pole positions in his class at every venue he attended. In 2017, instead of chosen entries, Grimes and Mowlem entered for the whole of the season, and at the end of the season they finished fourth overall in the endurance category and won the class 2 trophy. In 2018, Mowlem only attended one round of the season with Ivor Dunbar in a 488 GT3, winning both races in his category.