Cask ale (I hate the term real ale because all ale is real, irrespective of whether it is pasteurised) is performing well because, as you rightly say, there is an increasing range of styles and flavours in a dispense format that can not be replicated in a shop.

The growth of micro brewers has also contributed to this growth as progressive beer duty reduces the level of tax they pay. I fear you are incorrect though on the supermarket gnats pee as the vast majority of supermarket proprietary lagers are UK brewed.

Angry from Accrington (via website)