Graham, I recall you asked if I could find more on Polkinghonrne's views on idealism and realism. There is an interesting interview with him here:

http://www.crosscurrents.org/polkinghorne.htm

In it he says: Of course, Einstein was a very great scientist indeed, and I have enormous respect for him, and great admiration for the discoveries he made. But he was very committed to a view of the objectivity of the physical world. He wanted the physical world to be picturable, wanted it to be deterministic, and he wanted these things, I think, because he believed those qualities would guarantee the reality of the physical world. Like all scientists, Einstein believed very passionately in the reality of the physical world, and that we really learn something of its nature in our scientific investigations. I share that view with him, but I don't think that means we have to commit ourselves to a purely objective view of the physical world in the classical sense. It's clear to me that quantum theory (a theory that Einstein hated and never truly accepted), shows us that the world is more subtle, more veiled than that. Nevertheless, all of us who work in quantum physics believe in the reality of a quantum world, and the reality of quantum entities like protons and electrons. The basic reason we believe this is not because they are objective in the classical sense -- because they're not -- but because the supposition of their existence enables us to understand, to a great extent, physical experience. Thus, intelligibility is the guarantee of reality, rather than of objectivity. Incidentally, that was very powerfully and persuasively put forward by Bernard Lonergan.