Results of the MCMC fitting of the external depolarisation model on the Stokes I, Q and U channels to a polarised source with good signal-to-noise ratio. Panel a shows the measured flux densities per channel in black and the best-fit model in blue. Panel b shows the posterior distribution of the model parameters visualised as one and two-dimensional projections in a corner plot. Panel c shows the inferred polarisation fraction from the data and the best-fit model together with the residuals.