We discuss minimality conditions for the speed of monotone travelling waves in a sample of smectic C∗ liquid crystal subject to a constant electric field, dealing with both isotropic and anisotropic cases. Such conditions are important in understanding the properties of domain wall switching across a smectic layer, and our focus here is on examining how the presence of anisotropy can affect the speed of this switching. We obtain an estimate of the influence of anisotropy on the minimal speed, sufficient conditions for linear and non‐linear minimal speed selection mechanisms to hold in different parameter regimes, and a characterisation of the boundary separating the linear and non‐linear regimes in parameter space.