Berwyn Seismic+Meteor Explanation.
documentedgovernment_studyLandmark High-Strangeness Cases
Official/scientific account attributing Berwyn to a magnitude ~3.5 earthquake (with possible earthquake lights) plus a coincident bright meteor.
Junior RAF minister Brynmor John set out the position in a May 1974 letter: a meteor burning up explained the lights and the lack of any impact site, while the recorded earth tremor produced a landslide with detonation-like noise. The seismograph trace is documented; earthquake lights are a real but poorly understood phenomenon. A former MoD UFO-desk head accepts the quake but finds the meteor element harder to confirm.