[Hugin]

Traditionally Brits drank beer at cellar (not room) temperature. Pubs have been around a lot longer than refrigeration.

[Secret Agent Man]

50-55 degrees is a big step from 30-35 degrees, when you’re talking about a liquid you’re drinking.

[Daveinyork]

In German, it’s Kellerkalt, or cellar cold.

[Oratam]

Also, considering that beer traditionally in Britain means ale which ferments at about 70 degrees as opposed to lager which does its thing at a chilly 50 degrees, all those delicious complexities in ale would be lost on the tongue if the beer was served 'cold.'

Cool is best, especially in a country where it struggles to reach the 60s for much of the year.