In R, how to prevent blank page in pdf when using gridBase to embed subplot inside plot

I think it's a bit of a hack but setting onefile=FALSE worked on my machine:

pdf("test.pdf", onefile=FALSE)

In searching for an answer (which I didn't really find so much as stumbled upon in the forest) I came across this post to Rhelp from Paul Murrell who admits that mixing grid and base graphics is confusing even to the Master.