Are they trying to kill off a true British tradition in the biggest, most influential chain of Public Houses across our fair land?

Yes. They are.

Tim Martin's spokes-people seem to suggest that this is a "commercial decision". But how? It's popular, it's proper, it's perfect the way it is. Yes, you could put the prices up a tiny bit if that's really necessary BUT KEEP OUR SUNDAY ROASTS! We deserve that dry Chicken, tinned Beef, ruined Mashed Potato and barely defrosted Roastie.