An accessory mount assembly for mounting on a supporting structure of or associated with a vehicle. The accessory mount assembly includes a first portion having a first end wall and at least one side wall, a second portion having a second end wall, and a third portion having a plate portion and at least one mounting flange offset from the plate portion. The accessory mount assembly is configured such that, in use, a portion of the supporting structure of or otherwise associated with a vehicle is received between the first end wall and the second end wall.