kiwi,
I had the chance to do some "research" of my own yesterday.
I took a Micro-Tesla meter with me and stood under some lines around the district.
(Ok, so I was bored, but it made for interesting readings and some really strange looks from passing motorists) [Linked Image]
All of these tests were taken directly below the lines (ie: in the centre of the two 3-wire circuits on each side of the pylon)
with the meter held at eye level (1.79m):
  • 220kV circuit- Boundary Road: 0.37 uT
  • 110kV circuit- Laghmor Road: 0.52 uT
  • 500kVDC circuit- Cairnbrae: 1.16 uT
  • 66kV (1 circuit)- Pendarves: 0.08 uT
  • 22kV (1 circuit)- Tinwald: 0.021 uT
  • 11kV (1 circuit)- Boundary Road: 0.002 uT
  • 400V- In Town : Too low to measure.

I might add, that these tests were done with a TELARC calibrated meter.
Which raises the question about the meter used in the original documentary, was it in fact accurately calibrated?.