On receiving my fifth spam from Insured Health (I asked them to stop after the first), and on being told that no action can be taken because a key employee (a director) is on holiday (which appears to have been the situation for quite some time now), I decided that it's time I escalated this a bit, so I sent a complaint to the Direct Marketing Association.
They explained that, as Insured Health isn't a member, they can't take any action, but offered to forward the complaint to the Advertising Standards Authority; I hadn't intended it to go that for, but sine they offered, I agreed that they could do that. And the ASA have contacted Insured Health about this, which hopefully will incentivise them to take action.
While on the DMA web site, I found their Code of Practice, you can get that for free, I'd recommend it to all spammers (or, as they call themselves, "Direct Marketers"). I also found this at a similar web site:
This lets you opt out of email lists; I did that a long time ago, and when I checked yesterday, the opt-out was still current. It would be nice if spammers used this list to clean their email spamming lists. But I think many of them don't. Maybe it's only the reputable companies who use this. It costs a mere $2 per 1,000 records, or you can get their entire database as an Annual Subscription for Monthly updates: $1,800.
I understand that the relevant director of Insured Health will be back from holiday next week, so perhaps some progress will be made then. I haven't complained about them to the Information Commissioner yet; hopefully that won't be necessary.