Would a station in northern England be any use?

[G3WGV]

Thanks for that Andrew. I'm getting the materials together to build a coax loop (or perhaps just a wire one, haven't decided yet which is best?) and will take a look at what it picks up on my 'scope. Did you consider trying to get rid of the 81kHz signal with a series tuned circuit (notch)? Perhaps it doesn't matter, as the signal is not a broad-band pulse and I would imagine the controller has some sort of algorithm to reject non-pulse signals. Of course the VLF transmission might be strong enough to block the amplifier, forcing a gain reduction.

We do have electric fences around here occasionally. I hear their regular "transmissions" on the LF bands on my amateur radio station and they are very sharp spikes - easily eradicated with the noise blanker, unlike lightning.