1. A portable anomaly detection apparatus for inspecting an electrically conductive object, the anomaly detection apparatus comprising: an electromagnetic field emitter operable to pass a time varying magnetic flux field through at least a portion of the electrically conductive object, and thereby to generate an electrical eddy current field in the electrically conductive object, said electromagnetic field emitter including a magnetic flux focusing core; eddy current monitoring circuitry operable to survey at least first and second portions of the eddy current field, the first and second portions being non-coterminous; said eddy current monitoring circuitry including a first eddy field divergence sensor coil operable directly to sense eddy field divergence in the electrically conductive object; and signal processing apparatus connected to said eddy current monitoring circuitry, said signal processing apparatus being operable to compare data received from said eddy current monitoring circuitry observed at said first and second portions of the eddy current field.