As several others have suggested, I agree that the plant is a Crocosmia. It looks like a form of C. aurea or C. masoniorum or perhaps a cross between the two, of which there are several good examples, e.g. 'Comet'. the book to consult is Crocosmia and Chasmanthe by Goldblatt, Manning and Dunlop. Gary Dunlop owns Ballyrogan Nurseries in Northern Ireland and probably knows more about this genus in cultivation than anyone. His email address (which isn't a State secret, since you can readily find it via Google) is gary.dunlop[at]btinternet.com. He may be able to put a name on it for you.