Gamma-ray peak separations (Δ) vs. radio/gamma-ray phase-lag δ_g − r for gamma-ray pulsars from 3PC (coloured markers) and the MSPs studied here (black stars). For two pulsars, the definition of the primary gamma-ray peak is potentially ambiguous, and so for these we show the alternative values with empty markers, linked by dashed lines. Pulsars with only one gamma-ray peak are shown below Δ = 0 with a random scatter in the y-axis for clarity.