Depends what topic you're going for but the guardian or ft, tatler, London or new York review of books, times literary supplement etc would be found in eg a London club library. Economist too, it's a light but fun read.
Are you really saying The Guardian is higher-brow than The Economist? As a regular reader of both I would never have guessed it. (I'm not British, if it matters.)
It's probably the highest brow of the mainstream (ie, non FT) newspapers. It's seen as less try hard and pseudointellectual than the Economist i think.
The Guardian is probably the most often quoted publication in Private Eye's "Pseuds Corner", a regular selection of unintentionally amusing psuedo-intellectual writing.