A ground pentrating radar survey was carried out by Sumo Survey at the Mercury Theatre in 2018 in advance of excavation.<1> The site was divided into three sub-areas, which were investigated in separate phases of site work. Area 1 is located to the south of the theatre, Area 2 is north-east of the main building and Area 3 lies to the east of Area 1. Two GPR systems were utilised for the investigation. A GSSI SIR 3000 was used for Areas 1 and 2 and a GSSI Dual Frequency Radar for Area 3. The objective of the GPR survey was to search for evidence of archaeological remains. An orthogonal grid of radar profiles was completed over the survey areas spaced at intervals of 1.0 metre for Area 1 and 0.5 metre for Areas 2 and 3, where access allowed. The survey data was interpreted as individual radar profiles with the results presented as plan interpretations. The GPR survey identified a number of anomalous features potentially corresponding to archaeological structures, disturbed ground with structural fragments and anomalous layering that could be associated with foundations or buried floors.