10:30 p.m. (GMT). RAF pilot of Mosquito pursued unidentified radar target showing efficient controlled evasive action at 22,000 ft speed equal or greater than Mosquito, headed W? towards Norfolk, Eng. (FOIA) This was five months before the Kenneth Arnold sighting and the beginning of the Wave of 1947, followed by the crash at Roswell in early July. The incident was also linked to another "X raid" tracked by radar earlier that same day. An FBI document from July of 1947 quoted the Air Ministry case summary stating that: "no explanation has been forthcoming, nor has it been repeated." This information was not entirely accurate, because a very similar incident had occurred just 24 hours after the North Sea incident. As a direct result, Fighter Command immediately extended its night radar watch.

The U.S. got a full report on this which (Captain Edward) Ruppelt saw and summarized.  The summary was in Hynek's files now at CUFOS, Operation Charlie, which Martin Shough and Dave Clarke dug out of the UK archives.  This impressive case involves more than one incident, and the British archives is missing some information.  Apparently the Americans got a report on the incident including information that is now missing from the UK archives.