A dataset associated with the listed publication. Trapped field measurements taken as follows: The top and bottom faces of all of the YBCO samples were polished flat and parallel using 180 grit silicon carbide paper. The maximum trapped field at the top and bottom surface was measured initially using a hand-held Hall probe positioned approximately 0.5 mm above the sample surface. Subsequently, the trapped field profile across both the top and bottom surface of each single grain was measured using a rotating array of 19 Hall probes positioned approximately 1.5 mm above the surface of each sample. The samples had been field cooled at 77 K in an applied magnetic field of 1.4 T prior to trapped field measurement. The temperature of each sample was maintained at 77 K for the duration of each measurement.