Experiments carried out as part of a campaign of a JET Exhaust Task Force aimed at characterising divertor and scrape-off layer parameters [1] have also extended the database describing the dependence of the sub-divertor helium pressure on ELM frequency, configuration, and confinement mode. During the characterisation campaign the ELM frequency was varied with a scan in neutral beam power, whilst the configuration was varied by sweeping the separatrix from the corner to the vertical target in the MkIIGB divertor and L-, H-mode and ohmic conditions were obtained. Sub-divertor helium partial pressure was measured with a species-sensitive Penning gauge. When combined with the main results of the characterisation of edge and divertor parameters, this sub-divertor pressure database will in future permit more detailed modelling with the edge codes available at JET. As a preliminary step, a comparison is made of the measured divertor parameters with EDGE2D and SOLPS code results for typical discharges.