I get the impression that the school recreation ground would have been reasonably visible from approx. 100 metres away
It was 200 meters away. In fact I'm so confident of that, from the evidence presented, that I don't think it's helpful or accurate to use the 100m distance.
1. Google Maps shows the school boundary and the bush where the "glint in the trees" was - although I don't know who placed that pin. This map is from 2005, so 11 years later and some land features may have changed. The season is 4 months earlier (May = end-Autumn) than the sighting (September = early Spring). 100 meters away would place the UFO across the playing field and not in the bush and tall grass that we see in videos (below).
2. Guy points at the location and says it's "between the third [telephone] pole" which implies he's counting from the nearest pole (number 1) and then the sighting was either 2.5 or 3.5 poles away. I can't find Zimbabwe-specific info about pole span but 100m is "standard" in rural Uganda. (Spans are longer in flat rural terrain, shorter in built-up complex areas.)
Source:
PREPARATORY SURVEY REPORT ON THE PROJECT FOR RURAL ELECTRIFICATION PHASE III IN THE REPUBLIC OF UGANDA, JICA, 2012 (p. 2-7).
Guy pointing to the location. Source:
BBC interview, 1994, timestamped.
3. The site was on the cross-country trail (according to the adult kids, I think?). This isn't evidence for the distance of 200m but just for context: I don't know where that trail was, but by definition it's not purpose-built (like a regular athletics track) or it wouldn't be cross-country, so it was presumably further afield than the playing field area. According to
RunningShorts.com primary kids run 1 to 2 km for cross-country. The yellow line here is 1000 meters exactly and would take the children past the site, whereas running around the track would not.
(BTW the Westall sighting in 1966 was also associated with the school's cross-country trail, which was just some roads and tracks through a rural area beyond school grounds.)
4. Hind corrected the "100 meters" to "200 meters" her book
UFOs Over Africa, 1996:
p. 222
p. 229
Obviously the kids could
not see the features clearly at that distance, regardless of Hind's determination to present their perception as accurate. It's human nature to add details to a poorly perceived sighing (and especially to our memory of the sighting upon recall) if we already
think we know what we're looking at.
It seems improbable that a human-sized puppet could be seen in considerable detail, but that the puppeteers couldn't be seen and recognised as such, nor could their vehicle.
This video is on Hind's assistant Gunter Hofer's site and shows Gunter, Mackie and Hind trekking toward the site (timestamped) - some of the plants are as tall as them, and since they haven't yet reached the site, this vegetation is what would be obscuring the view:
19:09: Here's Gunter talking to a couple of the kids at what I presume is near the site, since they've stopped to discuss something and Guy is gesturing toward the right:
19:32 Here they're returning from the site back to the boundary log - it gives a good idea of the view the kids had in terms of vegetation: