Roger, I think it's just good in some locations. For instance, when you shop at Vons, Pavillions or Ralphs in Southern California, they double the coupon, so $1 becomes $2 off. In the San Francisco area, Safeway does not do this (they are somehow connected with Vons). The good thing is, many grocery stores have promotions to get you in the door. You just have to be on the lookout for them. Having said that, I wouldn't have noticed this sale and its benefits without onedog's post.
That could be your story when you get back to the UK. How I spent my free time in Detroit: going from supermarket to supermarket looking for Kellogg's deals.