A systematic methodology for the evaluation of various existing linearisation procedures sustaining mean field theories for nonlinear composite materials is proposed and applied to the ’modified secant’ and various ’affine’ formulations. It relies on the analysis of a composite for which an exact treatment of both the nonlinear homogenisation problem and the linear homogenisation of the ’linear comparison material’ with identical microstructure is possible; the effects of the sole linearization method can then be evaluated.