The term "Real Ale" was coined in the 70s to distinguish what in fact was the traditional method of producing beer from beers that were being sold as keg beers, which were heavily marketed by the major brewers at that time. (As a side note, beer and ale are one and the same today, but in years past were different, in that ale was an unhopped malt beverage, beer being hopped and consequently taxed at a different rate.)
The marketing strength of the major brewers was such that the more costly traditional beers were in danger of disappearing, and to prevent this occurring a group of enthusiasts created CAMRA, the Campaign For Real Ale. And what a wonderful job they did, and are still doing - rarely has a voluntary pressure group achieved so much in the commercial world.
The description of the old-fashioned beers as real ales helped drinkers to distinguish between those few real ales that were still being brewed, and the keg-type, which were not in the same league, being among other things very gassy. A result of CAMRA's efforts was the phenomenon of the so-called micro-breweries. These were small breweries started by enthusiasts, setting out to brew a few barrels a week, and to sell to local pubs. In so doing they naturally stood on the toes of the big brewers, but sense prevailed and after a struggle publicans were given the right to sell guest beers, which is where the micros, like Colchester Brewery, come in.
So what is real ale? It refers to living beer that continues to ferment and develop in the cask, (i.e. barrel), after it has been racked, (which means taken from the main brewing vessel and put into casks ready for sale), the yeast continues a secondary fermentation to enhance and condition the beer, to further improve the more intricate flavours, even though the main brewing process has been completed.
Brewers look to create a range of flavours in the beers they brew, this being dependant on the types of malt used, the variety of hops and other natural ingredients, and the target abv, (alcohol by volume). Some people believe that only high abv's result in full flavours, but this is not necessarily true, and low abv beers can have as much flavour as beers with a significantly higher abv. Since duty is levied on the abv % the best result for the customer is a delicious low abv beer - all the flavour at a lower price! Special ingredients can be introduced, such as coriander, which was in use long before hops became widely available.
So enjoy real ale, it's the "real deal", and has succoured the nation since Adam was a boy.