buddhu - 9:28 am on Jul 27, 2012 (gmt 0)
Actually, tedster, thinking about it (now I've had coffee) the redirect would take the user traffic to a page that was identical to the landing page blocked in robots.txt (which would be basically a dupe of our homepage). So, there should not be an issue with the user and Google seeing different content.
I guess the remaining issue is whether I could redirect that traffic in a way that doesn't pass pagerank, and that would satisfy Google.
This is now kind of an academic exercise. In practical terms, as I say, I'm fine with forgetting the redirect bit and leaving the traffic to fend for itself.