Best-fit parameters from the ageing model fits to the stripped tails. Data points are coloured according to galaxy and are consistent between panels. Top: distribution of best-fit injection spectral indices on a galaxy-by-galaxy basis. Error bars correspond to 68% credible regions from the posterior distribution. Bottom: best-fit break frequency as a function of distance along the tail. Each marker corresponds to a single measurement for an individual galaxy, and error bars span the 68% credible region. In the ℓ = 0 bin, upper limits correspond to galaxies with purely power-law spectra and are shown at v_b = 10 GHz, which is the upper limit of our prior distribution. To improve readability, in each distance bin data points are randomly shifted along the x-axis according to a Gaussian distribution with µ = 0 and σ = 0.5 kpc.