Miospores from the clastic intervals between the Robinson Limestone and the Peghorn Limestone in the Brigantian (Mississippian) stratotype section at Janny Wood, Cumbria, are assigned to the Tripartites vetustus–Rotaspora fracta (VF) Assemblage Biozone. The species Murospora parthenopia, normally considered to be restricted to the underlying Raistrickia nigra–Triquitrites marginatus (NM) Biozone, is also recorded. Tripartites vetustus is recorded from the stratigraphically deepest sample, meaning that the base of the VF Biozone lies within the Asbian and not at the base of the Brigantian. The base of the VF Biozone cannot be proven in Janny Wood. A review of independent palaeontological controls on the age of the first appearance of T. vetustus in Britain indicates a lack of stratigraphical precision at the local level.
Supplementary material: A full biostratigraphical range chart and a spreadsheet of biostratigraphical data are available at https://doi.org/10.6084/m9.figshare.c.4199306