The Rendlesham Forest incident

In late December 1980, USAF security police at RAF Woodbridge in England reported strange lights and a glowing object in nearby Rendlesham Forest. Astronomers and skeptics have tied the lights to a fireball and a lighthouse.

In a memo to the UK Ministry of Defence dated 13 January 1981, Lt Col Charles Halt of the USAF wrote that at about 03:00 two security police patrolmen saw odd lights beyond RAF Woodbridge's back gate. Suspecting a crashed aircraft, they got leave to go out, and three patrolmen went on foot. Halt says they reported a glowing object among the trees that looked metallic and triangular, roughly two to three metres wide at the base and two metres tall. Halt dated this 27 December; Wikipedia says it happened on 26 December 1980, and BBC News reports lights seen on both 26 and 28 December.

Wikipedia notes that astronomers have put the first lights down to a fireball of natural debris seen over southern England at around that time. Brian Dunning of Skeptoid (2009) cites Cabansag, one of the patrolmen, who reported that after leaving the base the sole light they saw was one all three came to identify as a beacon or lighthouse past a farmhouse, and that a yellow haze was the farmhouse lights. The men then walked back to base.

The story became public when The News of the World printed the contents of Halt's memo in 1983. David Clarke reports that the MoD said at the time the memo had gone to the staff in charge of UK air defence, who judged it of no defence significance.