Black to play. This position is a variation from Kramnik-Naiditsch, Dortmund 2015. How can Black make a decisive material gain? Answers to me at The Spectator by Tuesday 21 July or via email to victoria@spectator.co.uk or by fax on 020 7681 3773. The winner will be the first correct answer out of a hat, and each week there is a prize of £20. Please include a postal address and allow six weeks for prize delivery.

Last week’s solution 1 … Ba6

Last week’s winner Peter Durow, London W4