Why is my bread like a brick?

[SarzWix]

I try very hard to get mine to come out like the loaves made by Walk Mill in Cheshire, but even using their gorgeous flour, I just can't get it to come out the same.

[Plot10]

Success!!!!

Yesterday I picked up the latest in-store Co-op magazine which has a recipe for tomato and olive rolls so I thought I'd have a go. I decided to make 1/2 the quantity i.e 8 rolls rather than 16 but still used a whole 7g packet of yeast, don't know if that made a difference. I mixed the yeast with warm water and let it froth up before adding to the flour, I also added a crushed vitamin C tablet. I let the dough prove for an hour then knocked it back, formed into rolls and let prove again for an hour. After baking they were much lighter than my previous attempts. Thanks for all your help.