Radio colour-colour diagrams of T1 (top) and T2 (bottom). Data points are colour-coded based on their increasing distance from the core from blueish to reddish colours. The black dashed line (one-to-one line) indicates a power law with α = α_inj. The dotted lines represent the theoretical KP (orange), JP (blue), and TJP (red) ageing curves obtained with α_inj = 0.51 (T1), α_inj = 0.72 (T2), B₀ = 2.2 μG (T1, T2) as input. The frequency pairs and resolution are the same as in Fig. 8.