Known autonomous taxi systems for aircraft include a rigid connection between the aircraft wheel and a gear which is used to drive it. Such arrangements have been found to suffer from the problem that wheel deformation modes cause unacceptable wear and/or stresses within the drive system and/or wheel. The present invention thus proposes a drive system for an aircraft landing gear, the drive system comprising: a pinion gear; a drive shaft arranged to rotate the pinion gear about a drive axis; a driven gear arranged to mesh with the pinion gear to be rotatable by the pinion gear, the driven gear being connectable to a wheel of the landing gear to be capable of rotating the wheel about a wheel axis; and a flexible interface. The flexible interface comprises a plurality of driven gear coupling members, each driven gear coupling member having a first connection portion attached to the driven gear, a second connection portion adapted to be attached to the wheel at an offset distance from the wheel axis, and a joint between the first connection portion and the second connection portion, the joint permitting relative movement between the first connection portion and the second connection portion.