This fermentation process is by no means unique to ale, it is also commonly used in any number of traditional beers, notably the dopple and tripple beers from Belgium and Germany. The name was brought into widespread use in the United Kingdom, CAMRA (Campaign for Real Ale) work to promote real ale, as oppposed to the many keg beers that were being called ales in the UK during the 1970s.
There are literally hundreds of breweries in the UK which produce Real Ale and the list is ever changing. There is a steady erosion of some of the older names through closure or merger, but to offset this there are many new breweries, especially Microbreweries opening.
More information on which companies are brewing beer and where their beers are sold can be found in publications such as the Independent Imbiber and the CAMRA Good Beer Guide.
There are also a huge number of on-line resources for Real-ale information, among which the Beer Mad site is a reasonable start point.
See also; Micro brewery