No one likes a gossip … except perhaps the art world. This opaque realm of private views and hidden prices, often described as the last unregulated market, thrives on insider chatter and rumour. And little wonder. If you are among the first to find out information — whether the final illness of some serious collector or the financial worries of some troublesome competitor — you might be in the position to do good business on the back of it.

The latest subject of tittle-tattle is the auction house, Sotheby’s. The rising wave it has ridden over recent years — a wave that has frequently mounted to record-breaking heights, most recently in New York in May when Leonora Carrington’s Les Distractions de Dagobert sold for £22.5