This is probably for some so-called 'craft' beer and possibly with a high ABV. I drink in some pretty expensive London pubs and £5.80 is where cask beers top out, far less if drinking in an ale emporium such as the Wenlock, Southampton, Cock, Express etc.
On the plus side, Titanic Plum Porter £3.20 a pint for June at The Royal Blenheim.