This promotion is part of the ongoing aggressive war being fought by the supermarkets for footfal, with the sideaim of driving the specialist off licence out of business completely. The specialists are on their last legs anyway now, and had moved into local regional beers as something teh grocers wouldnt bother to kill. However the grocers have now gone in there too. It started with 3 for £5.50 and has escalated to 4 for £6. 5 for £7 is next, and 10 for £10 should be here pre Xmas.
The supermarkets have defined the role of beer in their trading strategy as a footfall generator, and are prepared to lose money on it because there is clear EPOS data to show that a multipack beer purchase is a door opener to a big shop overall. It triggers selection of a bigger trolley and then the shopper fills it.
As we get into the winter pre Xmas frenzy this becimes pretty essential to winning so we can expect this year to see a price war in beer again.
Nobody is making money in this beer market, and eventually it will collapse on itself, as the grocers will pass their losses back onto the producers.