This invention relates to a method of catheter and radiating coil location in a human body and in particular to the determination over time of the location of the tip of a catheter as it is inserted and during its use in the body. In particular when a radiating coil is used in conjunction with a catheter, a coil locating device can be used to determine the distance the coil is from the device and hence its depth in the body of a patient. To assist a clinician using the coil-locating device, a display is provided that shows both a reference image of a part or portion of a body (non-subject body) and an image of the coil located on the display with reference to the reference image. This is achieved by locating the coil-locating device on or over a predetermined landmark on the patients body. The coil and its associated signal wires can be incorporated into a stylet, guide wire or a catheter. The coil locating device has a preferable triangular shape in plan view that allows it uppermost apex to be orientated towards the head of the patient and for an axis of the device to be aligned with the mid sagittal plane of the patient. Preferable landmarks on a human body include the xiphoid sternal junction and the caudal/mid sagittal aspect of the jugular sternal notch
