Thanks Harold. I'm using 0.7.43 and I can't find anything in the Release notes about a change to the recipe since 0.7.40.
I think I know what's going on, and its nothing to do with the recipe. I think The Guardian are publishing the Media Guardian articles too late. I ran the recipe at 5am GMT. The Media Guardian articles were published at 7am, which is a bit of a shame. The articles in the other sections were published much earlier and downloaded ok.
I'll try downloading later next Monday and see what happens.