White to play. This is from Keres-Mardle, Hastings 1964. How did Keres ignite his attack? Answers to me at The Spectator by Tuesday 2 February or via email to victoria@spectator.co.uk or by fax on 020 7681 3773. There is a prize of £20 for the first correct answer out of a hat. Please include a postal address and allow six weeks for prize delivery.

Last week’s solution 1 Qxg7+

Last week’s winner R.F. Tindall, Great Shelford, Cambridgeshire