Posted: 09/02/2014 at 15:37
It may have been sieboldiana steve. It has blue, strongly ribbed leaves which are tougher than the more variegated ones, and the general consensus is that that's the reason they leave them alone. That said, I have one, and it was shredded last year by the giant snails that live here!
The self coloured ones tend to have tougher leaves anyway, so you might want to favour those. There's been lots of discussion on here about remedies to keep slugs away, from beer traps and grit, to garlic washes and night time hunting with a torch!