Since the beginning of in-situ plasma measurements there has been extensive use of instruments utilising a retarding potential for the determination of the energy of the detected particles. Most of these instruments, however, were detecting the total current generated from the incidence of the charged particles onto a collector. The limitations of the current measuring equipment's sensitivity and the expected plasma density dictate the size of the collector area. In the current trend for cheaper, faster, smaller missions this could be a significant limitation. Presented here, is a retarding potential analyser (RPA) utilising a microchannel plate detector and, thus, offering great scope for miniaturisation. The sensor incorporates a dual RPA structure to prevent UV generated events. The above structure gives a differential energy response with a FWHM that depends on the percentile voltage difference of the two RPAs. Due to the fact that there is no direct path from the entrance of the instrument to the detector, the energy response is highly dependent on the shape of the grid that supports the second RPA. The CID was flown upon the STRV 1A spacecraft, where its primary role was to provide information on the effectiveness of the Active Neutralizer Experiment in reducing the spacecraft potential. A preliminary analysis and validation of the collected data is presented here.