Thanks for all your suggestions. I went with the foil idea as the size of the roast required a long cooking time which would have burnt/blackened the vegetables, (which I did not have many to spare). It turned out great.
I love a good roast.
"That's why they put mirrors around fruit at the supermarket. So when you see yourself you say 'Oh crud I'm dying I better eat some of this stuff!'" (Dylan Moran)