They do (arguably but definitely in my opinion) deliver a much better quality pint than the keg variety. Keg beer bought in, in the 60s I think, although invented a lot earlier, by breweries as it was a lot easier to keep and dispense a sterile beer rather than a live beer, plus the wasteage was less. I'm sure many will remember the (non) joys of Watneys Red, Double Diamond and Whitbread Tankard (that we used to Spoonerise). I have one or two engines kicking about the house somewhere, I wil have to rekindle my brewing prowess. Eeeh I remember when it were all fields you know.