Yes - there's only one that's reliably hardy in the UK, and that's Zantedeschia aethiopica 'Crowborough'. All the others need to be taken into a frost-free place to die back and dry off until they're started back into growth in the spring.

That is quite correct. None of the Zantedeschia's are hardy apart from Z. aethiopica 'Crowborough'.

By the way, why would you think that being on the coast would make the winter worse? If you are at the coast you are more moderated in winter so milder than inland. My auntie who lives near Wolverhampton gets some winter temps. much colder than I do living near the coast in Northumberland.

Fractal, I think that's possibly what this guest is saying - that in view of the fact that he/she does live near the coast, would the Zantedeschias be OK outside? The answer's still the same, though!

Yes, I see how it can be read that way too. Wasn't disagreeing with your info either of course. Perhaps if they had said "even if" to be clearer. Being a guest we may not get an update on this of course :-)

No, I shouldn't think so. Some guest questions really do need clarification, don't they...I often have to 'assume' or 'guess', not always corrrectly, I'm sure!