Observed spectra and the difference spectrum of the turning off CLQs. The quasars shown are J0823+4220 (top two panels), and J0126–0839 (bottom two panels). Upper: the observed optical spectra, with the first epoch (black) and second epoch (red) both shown. Lower: the difference spectrum |Δf_λ| (black) is shown, demonstrating how the CLQs were identified, and the resemblance of the variable component to an accretion disc. A fitted Shakura-Sunyaev accretion disc power law f_υ ∝ υ^1/3 (dashed-blue) and a best-fit power law to the continuum (orange) is shown.