Everyone can play a part in ensuring that the supermarkets will listen. Hit them in the pocket !!
Find a reputable butchers, ask where he sources his products. I gave up on buying meat from the supermarket about 10 years ago and only buy the other things i need from them - sugar, flour etc. Most recently i have found a local farm shop so i dont buy my vegetables from the supermarket either.
Its laziness and convenience that makes us buy all food products from one place, i dont have a car but i would prefer to walk the 2 miles each week between the butchers, farm shop and tesco's than eating steroid/pesticide laden food.

Good on you Jamie/Gordon and Hugh for keeping this issue in the publics eye.