I've heard there is controversy surrounding Quorn but I've never actually seen any.
Quorn is a mycoprotein, a meatless substitute that derives from fungi. It is by far the most delicious meat substitute out there. I suggest trying to implement that into your meals. They make quorn in all kinds of varieties, from grounds (ground beef sub) to chunks (for chicken sub) to meatloaf, sausages, lasagna. You name it, quorn can do it.
http://www.quorn.com I believe is the correct site. It may help a lot with the substitutions and you won't have to go too far out of your way for your vegetarians when you're cooking.