text: © Licensed to London News Pictures. 16/11/2018. LONDON, UK. Technicians present "The Joke", 1923, by William Roberts (Est. GBP300,000-500,000). Preview of Sotheby's autumn sale of Modern & Post War British art. Works from the British art scene of the past century will be offered for sale on 20 and 21 November 2018 at Sotheby's in London. Photo credit: Stephen Chung/LNP