Unfortunately not. I'd already followed similar instructions without success - although wolsniffer was very useful in confirming that the packet was being forwarded.
I suspect that it's related to the ARP entry that several of the comments to the article spoke of. If I shut the PC down and then immediately use the WOL app on my iPhone, the PC will restart. But if I leave it switched off for 10 minutes (or so), it no longer responds.
I can't find any instructions on how to create a static ARP entry on an EE BrightBox - telnet/SSH just closes the connection. Therefore the recommended solutions to this problem aren't an option.
Thanks for your suggestion.