The recently synthesised molecular magnet [Sm(hfac)3(boaDTDA)]n is the first metal complex of a thiazyl-based neutral radical ligand to exhibit ferromagnetic ordering, with Tc =3 K. This is of special interest, not only as it increases the relatively small number of radical ferromagnets yet discovered, but as its cooperative properties appear to realise a model developed by McConnell which ascribes intermolecular ferromagnetic interactions to overlaps from regions with opposite spin density. Here we propose the first muSR study of a fascinating class of magnetic materials based on [Sm(hfac)3(boaDTDA)]n. Our aims are to probe the transition to the magnetically ordered regime(s) in the Sm-based system, along with the related dynamics, and then to investigate an analogous system where the lanthanide ion is La(III) and whose magnetic ground state is currently unknown.