Hello,
I have another type of difficult house to insure: a protected structure with a leaky roof. Most insurers got badly hit (or so they say) with the flooding and snow this winter so getting insurance is tougher for everyone.
One broker was able to help me in the end (essentially the house will be classified as a building site while I repair the roof): self built insurance (aka Hooper Dolan). They said that the insurance could be transformed into a normal house insurance once the work is done. The insurer is actually British, so they might not be aware of subsidence in Cork...
Another broker that didn't laugh in my face was O'Leary Brokers in Cork. I didn't pursue as they said that the quote I got from the other guys was to good to match.
I know your issue is a different one to mine, but I throw these names in as being in the only two who didn't give me a straight no.
Good luck with it.
Solene