Much more of a coincidence than I first posted....
In 1983, Black Sabbath put out an album called "Born Again", which had an instrumental called "Stonehenge." For that tour, the set was going to include a reproduction of Stonehenge, but they screwed up feet and meters. So instead of having a Stonehenge that was 15 feet high, it was 15 meters high and wouldn't fit in any of the venues. They didn't even have anyone named Nigel in the band at the time, so they didn't really have an excuse.
Now, you'd think that this incident must have been the inspiration for Spinal Tap's Stonehenge bit. But you'd be wrong.
The truth is that Spinal Tap was being pitched by Rob Reiner in 1981-82, and they shot a 20 minute version that included the Stonehenge bit - dwarfs and all -- in that pitch. But the Sabbath song didn't even come out until 1983, and the issue with the props being too big didn't happen until October 1983. So even though This is Spinal Tap came out early in 1984 after that Black Sabbath Tour incident,
Spinal Tap had filmed their Stonehenge bit 2 years before Sabbath did it in real life, by accident.
Here's everything you need to know about the infamous Spinal Tap Stonehenge scene from the 1984 film This Is Spinal Tap.
methodshop.com
I didn't believe that could possible be true, but sure enough, the original Spinal Tap pitch clip from 1982 is actually online right here. The guys are younger, different haircuts, etc. Stonehenge begins at about 4:20:
Here's an interview with Ian Gillan, who was Sabbath's vocalist at the time, talking about the first show of their tour where they did manage to get their oversized Stonehenge inside. What actually happened to them might be even funnier than Spinal Tap..."
and that was the end of the dwarf".