Is this the world’s most exclusive book fair? Inside Firsts London, where the smart set spend a fortune on the rarest first editions

So, aside from those lucky librarians, who’s cashing in? Well, let me tell you that the atmosphere on this Thursday night is palpably buzzy – I’ve been to bars that were less lively – and the corridors of the Saatchi are jam-packed only 30 minutes after doors opened. Forbes tells me that there are approximately 3,400 billionaires in the world, and I hazard a guess that not all of them can be here tonight off Duke of York Square. Instead, the space is filled with characterful book…