Recently, we have shown that if the graphene lattice is doped with sulphur, ferromagnetism can emerge once the doping threshold level is overcome [10]. In particular, graphenes doped with 4.2 at.% of S showed strong ferromagnetic properties below ~62 K with a saturation magnetization reaching ~5.5 emu/g, which is among the highest values reported so far for any graphene-based system or even carbon-based (nano)material . Similar effects were also observed in N [11] and F/OH [12] functionalized graphene which show a weaker magnetization with respect to S. The investigation of this exotic magnetism with muons is of fundamental importance as, according to our past experience, µSR is the only technique allowing to inequivocally proof the onset of long range magnetic order carbon based materials.