A good reference library, expertise and access are paramount for any rare book dealer, says Paul Foster, who has been in the business for 27 years. ‘Knowledge is what I am selling, aside from the book,’ he says. He doesn’t do ‘investment speculation’, but he does say that good books are always popular, particularly rare books in good condition on travel exploration, economics or science. Clients also come in search of corporate or personal gifts or for advice on how to enrich their libraries. A recent highlight was coming across a complete set of first editions of Captain Cook’s voyages from the 18th century — it comprised all three voyages in nine volumes complete with an atlas in mint condition, and commanded a six-digit price-tag.