Assap’s UFO cases have dropped by 96 per cent since 1988, while the number of other groups involved in UFO research has fallen from well over 100 in the 1990s to around 30 now.

Among those to have closed are the British Flying Saucer Bureau, the Northern UFO Network, and the Northern Anomalies Research Organisation.

As well as a fall in sightings and lack of proof, Mr Wood said the lack of new developments meant that the main focus for the dwindling numbers of enthusiasts was supposed UFO encounters that took place several decades ago and conspiracy theories that surround them.