26 December 1980
and 28 December 1980 (early hours), according to an article (rendlesham-forest-mod-article) by
joint Royal Air Force-U.S. Air Force bases at the time of the UFO incidents.
Wikipedia article: “RAF Bentwaters”:
On 8 July 1958 Bentwaters was operated as ‘twin base’ with RAF Woodbridge and as a single unit under the newly designated 81st Tactical Fighter Wing. Along with the 91st and 92nd squadrons, the 78th Tactical Fighter Squadron was transferred from RAF Shepherds Grove when the USAF returned Shepherds Grove to the Ministry of Defence (MOD). The 78th TFS operated from Woodbrige, while the 91st and 92nd squadrons operated from Bentwaters.”
Map of RAF Bentwaters, RAF
December 1980 UFO landing site (2.bp.blogspot.com image)