An experiment is described in which a nominal normal shock impinges on a turbulent flat plate boundary layer. The wall pressure distribution in the interaction region was measured for Mach numbers in front of the shock of 1.40, 1.44 and 1.46. The Reynolds number based on shock position was 18 X 10(6) and based on momentum thickness at the start of the interim action 2 X 10(4). At all Mach numbers detailed pitot and static pressure surveys were made. The velocity profiles were integrated to give the integral properties whereas the skin friction was derived from Clauser plots. Increasing the Mach number results in a rapid growth of the separation bubble accompanied with the development of a supersonic tongue. A comparison with other data suggests that the Reynolds number also has a pronounced effect on the length of the separation bubble.