Free radical one-step polymerisation of methyl methacrylate in the presence of a crosslinking comonomer and balancing levels of a chain transfer agent allow facile high conversion synthesis of polymers with a branched architecture. Broad GPC curves have been obtained for these materials and branching has been demonstrated using GPC coupled with a triple detection system allowing evaluation of g', the Zimm branching factor. In addition the bridging residues in branched polymers arising from use of an unsaturated crosslinking comonomer have been chemically cleaved to yield the linear oligomers of much narrower molecular weight distribution that comprise the branched structure. The methodology promises to be generic, utilises only readily available starting materials and holds out good prospects for providing branched vinyl polymers on a technically useful scale at low cost.