I'm not sure I understand why Marstons are increasing the strength of bottled Pedigree.
They've kept the recipe the same yet have changed the process and this has resulted in a stronger beer which now tastes more like the cask version. In my opinion the best process they could have changed is the pasteurisation process. Make it bottle conditioned and maybe then it'll taste like its cask brother.
Better still brew it like they did in the 1980s; there is no doubt in my mind that the present Pedigree is a sad reflection of what it used to taste like.