Monday’s puzzle elicited some lively discussion on WhatsApp and elsewhere.

It was taken from the final of the Metropolitan section of the 1938 Kent Individual Championship, with Reginald Charles Noel-Johnson playing White against Francis George Tims Collins.

More experienced players would have identified the position as ripe for a double bishop sacrifice: a standard tactical idea with which everyone should be familiar. But before you go around giving up your pieces you have to calculate whether or not it works.

In this case, you’ll be gratified to hear, it does.

It goes like this.

20. Bxh7+! Kxh7
21. Qh5+ Kg8
22. Bxg7!

Now if 22… Kxg7 23. Qg5+ Kh8 24. Rd3/4, Black can give up his queen by playing f6, although White should still be winning. White does better here to throw in 24. Qf6+ Kg8 before playing 25. Rd4 (but not 25. Rd3? Bxh2+ 26. Kh1 Qf4). Here White is winning too much material, so Black chose to decline the second bishop.

22… f6

White found the strongest continuation.

23. Qh8+ Kf7
24. dxe6+ Kxe6
25. Re1+ Kf7
26. Bxf8 Rxf8

Or 26… Kxf8 27. Rd4

27. Rxd6! Qxd6
28. Qh7+ Ke8
29. Re1+

Black resigned: he’ll be two pawns down with his king still exposed.

Thanks to all who contributed to the discussion and well done everyone who worked out most of the analysis.

If you haven’t seen a double bishop sacrifice before you’ve learnt an important idea. If you have, you were presented with what I hope was an interesting analytical exercise.

You can find out more about the winner here. Part 2 will be following some time next week.

Here’s the complete game: click on any move for a pop-up window.