Asked to name a reference book, you may well choose the Encyclopaedia Britannica or the 20-volume Oxford English Dictionary. But perhaps you’d pick something less elephantine — the Guinness Book of World Records, with its tributes to figures such as Smudge, holder of the record for most keys removed from a keyring by a parrot, or Brewer’s Dictionary of Phrase and Fable, which informs us that the Russian equivalent of ‘to carry coals to Newcastle’ is ‘to go to Tula with one’s own samovar’.