  We look at the magnetic field induced weak localisation peak of graphene
samples with different mobilities. At very low temperatures, low mobility
samples exhibit a very broad peak as a function of the magnetic field, in
contrast to higher mobility samples, where the weak localisation peak is very
sharp. We analyze the experimental data in the context of the localisation
length, which allows us to extract, both the localisation length and the phase
coherence length of the samples, regardless of their mobilities. This analysis
is made possible by the observation that the localisation length undergoes a
generic weak localisation dependence with striking universal properties.
