We investigate the growth of wurtzite GaN along the non-polar [1 (1) over bar 0 0] direction on gamma -LiAlO2(1 0 0) by plasma-assisted molecular beam epitaxy. The morphological and structural properties of buffer layers and their orientation-relationship to the substrate are examined by means of reflection high-energy electron diffraction, atomic force microscopy, X-ray diffraction and Raman scattering. The layers are shown to be single-phase GaN(1 (1) over bar 0 0) within the measurements' sensitivity. In contrast to the ubiquitous C-plane GaN[0 0 0 1] orientation, M-plane wurtzite nitrides are expected to be free of electrical polarization along the growth direction. This is experimentally verified by the absence of internal electrostatic fields in (Al,Ga)N/GaN quantum wells as evidenced by continuous-wave and time-resolved luminescence.