Detective Constable Gary Heseltine, founder of the unique PRUFOS (Police Reporting UFO Sightings) records system, highlighted the almost-forgotten incident in the skies above the town as one of major "Defence Significance".

And - despite its initial logging on police files 25 years ago - Gary insisted that there was STILL NO convincing logical explanation for what happened above Bold Power Station in January 1978.

Then onlookers watched in disbelief as a shining light buzzed the installation, and appeared to dart down to take a closer look. But none were quite as astonished as two patrolling police officers who immediately logged in the spectacular sighting with disbelieving colleagues in the radio room.

DC Heseltine - a serving CID officer with British Transport Police in the South of England - explained : "The Ministry Of Defence still maintains that there has never been a case of Defence Significance. As a police officer, I find that position untenable and here is why.

"Having served in the Armed Forces I know that in the event of war in this country, all types of installation throughout Britain have been categorised for importance and vulnerability. For example oil fields, power stations, military installations and all key enemy targets which if hit would affect the infrastructure of Britain."

And he added later: "It follows that any attempt to survey or interfere with these types of installations would by definition have to be of 'Defence Significance'."

The PRUFOS dossier contains 84 official sightings - reported by a total of 212 policemen and policewoman in the years between 1950 and 2002. And researcher Heseltine highlighted the St Helens incident as one of the three MOST significant to take place at official installations during the Seventies while the Cold War was still raging.

But the serving sleuth claimed the speed of the craft over Bold indicated other-worldly powers, rather than a top-secret Soviet spy plane! Chronicled as No 44 in the database, the report observed: "Two uniformed officers - PCs Lowe and Roberts - observed a high speed UFO that hovered above Bold Power Station before darting across the landscape and doing likewise over Fiddler's Ferry Power Station.

"This occurred during the Cold War and again multiple police witness corroboration was provided. Power Stations would be targeted in the event of war in Britain, and are thus regarded as key installations from a national defence point of view."

Gary, who believes that Ets may have been monitoring the strategic strengths and weaknesses of various world powers, also highlighted two important instances of St Helens style incidents.

In August 1976, a craft hovered over Buncefield Oil Terminal near Hemel Hempsted for several minutes before vanishing.

The report - No 35 in the PRUFOS records - noted "Checks with Luton Airport ruled out conventional craft".

Some years earlier in October 1967, two policemen spotted a stationary UFO hovering above HMS Dolphin - a submarine base - for several minutes.

UFO expert Heseltine - one of scores of police officers to go public about strange phenomena - said later that the St Helens incident indicated an extra-terrestrial visitation.

The researcher - one of the main contributors to a new commercially available UFO video called 'Hard Evidence V11' - confirmed: "There is excellent circumstantial evidence that points to the craft being a genuine UFO."