A little context re the mysterious "Sam":
The area from a 1961 OS map:
The children are described in
the BUFORA report as playing "...
near Lake Common, Sandown...", which isn't particularly helpful as the Common covers a large area. There is, however, a Lake Common Road, which runs N to S, petering out into woodland at its north end. This seems to align nicely with the start of a footpath marked on a Victorian 25" to the mile OS map. I've starred this point on a more modern OS map:
The footpath marked on the Victorian map follows a course roughly towards the WNW and the Isle of Wight airport, which accords nicely with "Fay's" account:
Line of footpath dotted
1 = North end of Lake Common Road/start of footpath
2 = Footbridge over Scotchells Brook
The footpath continues generally WNW towards where the modern airport lies. Note that - shortly west of the footbridge - the path crosses the line of a Victorian long-range rifle range, between the 600-yard and 500-yard firing points.
A study of the 25"/mile map reveals two other footbridges crossing Scotchells Brook; they are, respectively 2,905 feet NNW of the footbridge marked (1) on the map, and 1,703 feet SSW of it, as the crow flies. I think we can dismiss these as being "Sam's bridge": No footpath leads to the southern one, and it parallels rather than approaches the airport; the northern one has a footpath leading to it, but is far north of the airport.
The relevant 25" OS map covering the area.
I note that the father of "Fay" was the man who reported his two UFO experiences in the BUFORA article; this wasn't clear to me initially.
Here's a theory:
1. I used to belong to a rifle club that used a 1,000+ yard range. This rifle range was crossed by a public footpath. To comply with the rules - and common sense! - the club was required to post members at the points on each side of the range to (a) Warn members of the public that there was a danger area ahead, and (b) Radio the Range Conducting Officer to order a ceasefire if said MOPs insisted on continuing across the range. Britain's climate being...
unpredictable...shelter was provided for the club members so tasked. I can imagine a Victorina rifle club providing a (semi) permanent shelter at the point where the path crossed their line of fire. Suppose that said structure survived the closure of the range and the development of the runway...
2. "Fay" and her chum heard "...
a weird wailing noise not unlike an ambulance siren..." Could this have been a siren alerting airport staff to a fire drill?
3. Suppose that (1) and (2) are correct. An airport fireman, dressed in firefighting kit, is stationed on the east side of the runway. Some time had passed - enough for a seven-year-old to have wandered over to see what was happening. Perhaps Mr. Firefighter had slipped off towards the (putative) Victorian hut to have a crafty fag. Having a look around the area, he drops something - his clipboard, with details of the day's exercise? - into Scotchells Brook off the footbridge. Cursing, he wades in to retrieve it. As he emerges, he sees two kids staring wide-eyed at this apparition, perhaps wearing a personal radio and associated antenna, plus a hand mike with PA system.
The kids ask the obvious questions, "Sam" decides to play along...
"Fay" seems to have come from a background not resistant to woo, her father reporting two brushess with high strangeness in the area. "Fay's" encounter, followed by weeks of Chinese whispers with her unnamed playmate before she told her father about it, might well account for this incident.
maximus otter