Study flow diagram. Historical samples likely to contain SARS-CoV-2 neutralising antibodies, and negative controls, from human participants or experimental macaques, were used to evaluate the various prototype stages during development of a novel lateral flow based neutralising anti-SARS-CoV-2 antibody assay. CVD, AH, NRL, SRST, AIMS and COR are historical sample sources (described in Table S1). Created with BioRender.com.