This contribution describes an approach that has been taken to asssess the quality of samples of the London Clay before laboratory testing. The approach involves the sinking of three co-linear boreholes, each with a specific sampling philosophy and method, and in which in situ shear wave velocities are measured using downhole and crosshole techniques. On sub-samples from rotary cores taken from one of the boreholes, measurements are made of Vvh, Vhv, Vhh using bender elements and of suction using the Imperial College suction probe. By comparing at equivalent stress levels the shear wave velocity measurements made on the sub-samples with those made in situ, the quality of the rotary cores can be assessed and the appropriate samples selected for advanced laboratory testing.