Best-fit Hubble constant and its uncertainty obtained in this study compared to the SH0ES result. The tilted purple lines indicate levels of discrepancy with the Planck measurement of the Hubble constant assuming a flat ΛCDM cosmological model. The blue and red arrows and the corresponding annotations describe the main cause of the apparent decrease in the best-fit H₀ between the SH0ES measurements and model A of this work, and between models A and B of this work. The new supernova modelling developed in this study results in a decrease in the discrepancy between the SH0ES and Planck H₀ values by at least 30 per cent (model A) and up to 50 per cent (model B).