The solution to Monday’s puzzle (Mate in 2: ‘Wartocress’ 1 Pr Busmen’s Chess Review 1968-69) is:

1.Rc1 Qd4+ 2. Rc5#

or 1… Kd4 2. Nc4#

or 1… Nxb3 (or anywhere else) 2. Nc4#

or 1… Bxg4 2. Nxg4#

or 1… Qxb2 2. Qxb2#

In the starting position White has a mate set for every Black move but is unable to maintain the status quo.

The rather improbable Rc1, allowing the black king a flight on d4, is the only way to force mate in two moves.

There’s also a changed mate after Qd4+, which would have been met simply by Bxd4 in the set play.

Well done to everyone who solved it correctly. I think Simon was the first to find the solution in our WhatsApp group.