“We got London on the track” is the famous drop, spoken by Skooly of the Atlanta rap group Rich Kidz, that helped turn producer London Holmes into a brand name. But it was one of the group’s contemporaries, Young Thug, that brought London On Da Track’s beats to the Hot 100 with a series of hit collaborations with Rich Gang, Tyga, T.I. and others. And over the course of Thug’s solo releases, particularly the Slime Season series, London On Da Track has emerged as the rapper’s most indispensable producer. His rich piano chords, swirling synth lines, and crisp, swinging percussion provide the musical heft for Young Thug’s best songs, allowing the iconoclastic rapper to experiment with his elastic voice over a solid foundation.