I think you're deliberately missing the point mr Steev. You can eat what the bleeding hell you like, but that doesn't stop the meal being affected and often diminished by having to make alterations for veggie eaters.
At the root of it, the sunday roast is an English tradition heavily based around a chunk of roasted meat, with an integral gravy made out of the juices of the joint. It's difficult to make anything as simple and coherent as a veggie alternative.
If we had a tradition of roasting veg and filo pastry parcels on Sunday others would see the Brits very differently. The French would have to call us the Roast Parsnips instead of the RoastBeefs for a start or more likely, those big effete ponces from over the channel