This morning I did some better experiments and set the IC706 up on a dummy load and placed the ICF-2001 receiver close by to the dummy load. I was easily able to detect the keying on the receiver, so that was excellent news.
The next challenge will be to find some sort of antenna matching arrangement. I have ordered a ferrite rod from eBay (despite trawling through my junk boxes in the loft, I couldn't find one). My first attempt at an ATU will, I think be similar to Roger G3XBM's - although more of a bodge I expect!
However, I was speaking to Adrian G4GDR yesterday on 2m. Adrian has been one of the 500khz permit holders and mentioned that he had made a variometer out of a carpet roll and some rods. He very kindly invited me to inspect it, which I will certainly do.
I'm not sure how viable the IC706 will be for 472khz, but perhaps it will be possible to scrape a local contact or two.