Parameter constraints from CMB lensing alone in the ΛCDM model (samples, colour-coded by the value of the Hubble constant) using the minimal priors described in the text; grey bands give the corresponding 1σ and 2σ constraints using the approximate fit of Eq. (13). Solid coloured contours show 68% and 95% constraints when additional information is included: BAO data from SDSS and 6DF (Anderson et al. 2014; Ross et al. 2015; Beutler et al. 2011; blue), and the same but fixing the CMB acoustic-scale parameter θ_MC to a CMB power spectrum fit (red; θ_MC = 1.0408). Solid black contours show the constraint from the Planck CMB power spectra (Planck temperature+low-ℓ polarization).