Model simulations undertaken by the Quantifying variability of the El Nino Southern Oscillation on adaptation-relevant time scales using a novel palaeodata-modelling approach (QPENSO) project. These are coupled ocean-atmosphere experiments with a modified version of the HadCM3 (UM version 4.5) climate model. The model has been modified to include stable isotopes of oxygen in both the ocean and atmosphere sub-models, after Tindall et al., 2009. The simulations are grouped into two experiments: 1) 'picontrol', comprising a single 750 year duration unforced pre-industrial boundary condition simulation; 2) 'forced', comprising a suite of six historical simulations of the interval 1160-1360 AD and including changes in solar, volcanic and greenhouse gas forcing. The six simulations represent an initial-condition ensemble over this interval.