We describe a likelihood analysis using MasterCode of variants of the MSSM in which the soft supersymmetry-breaking parameters are assumed to have universal values at some scale M_mathrm{in} below the supersymmetric grand unification scale M_mathrm{GUT}, as can occur in mirage mediation and other models. In addition to M_mathrm{in}, such ‘sub-GUT’ models have the 4 parameters of the CMSSM, namely a common gaugino mass m_{1/2}, a common soft supersymmetry-breaking scalar mass m_0, a common trilinear mixing parameter A and the ratio of MSSM Higgs vevs tan beta , assuming that the Higgs mixing parameter mu > 0. We take into account constraints on strongly- and electroweakly-interacting sparticles from sim 36/fb of LHC data at 13 TeV and the LUX and 2017 PICO, XENON1T and PandaX-II searches for dark matter scattering, in addition to the previous LHC and dark matter constraints as well as full sets of flavour and electroweak constraints. We find a preference for M_mathrm{in}sim 10^5 to 10^9 ,, mathrm {GeV}, with M_mathrm{in}sim M_mathrm{GUT} disfavoured by Delta chi ^2 sim 3 due to the mathrm{BR}(B_{s, d} rightarrow mu ^+mu ^-) constraint. The lower limits on strongly-interacting sparticles are largely determined by LHC searches, and similar to those in the CMSSM. We find a preference for the LSP to be a Bino or Higgsino with m_{tilde{chi }^0_{1}} sim 1 ,, mathrm {TeV}, with annihilation via heavy Higgs bosons H / A and stop coannihilation, or chargino coannihilation, bringing the cold dark matter density into the cosmological range. We find that spin-independent dark matter scattering is likely to be within reach of the planned LUX-Zeplin and XENONnT experiments. We probe the impact of the (g-2)_mu constraint, finding similar results whether or not it is included.