You're right about Swan, John, and I respect Swan (although I admit to not always clearly understanding what he says)....in Michael Swan's book"Practical English Usage", there are five sections on the use of the subjunctive.
But even so, notice the language he uses in speaking about the subjunctive: "The subjunctive is not very common in modern British English, and is used mostly in formal style. [Emphasis mine]. Ideas of this kind are usually epressed in other ways." I submit that it's also not very common in modern American English.
He also says, in section 3: "The subjunctive form were is often used instead of was after if, as if, and I wish. ...Was is also possible in these cases, and is more common in conversational English."
So Swan, to whom I'll gladly defer, admits the existence of subjunctive form, but seems to suggest that it is on the way out of the language. That's pretty much what both you and Iain said. I stand corrected.
Larry Latham