The origins of Duet for One lay in a private puzzle that I set for my father’s 80th birthday in 2008, where solvers were required to darken the cells with letters not present in his full name, such that the figure 80 appeared in the completed diagram.
This led me to wonder whether it was possible to construct a diagram where darkening certain cells would lead to a traditional blocked diagram, which could then be solved as well.
Since there would be fewer clues in the blocked diagram, maybe it was possible to contain all the necessary instructions and the secondary clues by means of a single word added to each primary clue.
At the same time, it struck me that it would be good to hide a message in the second diagram that somehow related back to the original diagram, leaving only one diagram to be submitted but in a way that showed that the second diagram had been substantially solved correctly. Hence the advent of the “Buy one get one free” idea, leaving BOGOF to be highlighted in the primary grid.
The two halves of the alphabet were the obvious way to separate light and dark cells (particularly with “atom” being a convenient extra word to cover this concept), and this led naturally to trying BOGOF in at the top of the leading diagonal, giving a normal blocked grid pattern in the NW corner. In retrospect, this was probably a mistake and I wish I had put a red herring into those five squares to catch out the unwary – or more particularly those who would just assume these were the five letters to be highlighted….
The reason that I did not subsequently change this was that the diagram turned out to be quite tricky to fill. In fact more than once I despaired of ever filling it. But with patience it gradually fell into place, and for once, the number of short words was less of an issue, because I needed more clues to fit in all the instructions and the secondary clues.
The clueing itself was not so difficult, although having to fit specific words into the clues led to less flexibility in clueing, with the result that many clues were constrained by the material to be included.
Titling is usually the last thing that I do, and my Listener puzzles have usually had musical titles. That led to the thought of Duo or Duet and hence to the title actually used.
An initial version of the completed puzzle went to the Listener vetters. This is an appropriate time to pay tribute to their guardianship of the quality of the Listener crossword – and their own powers of crossword compiling. As well as a number of suggestions to improve clues, they suggested an important improvement to the grid (removing a marginally offensive word) and – most importantly – suggested that the whole thing would be neater if the break between the secondary across clues and down clues coincided with that between the primary across and down clues (which was not the case with the puzzle as originally submitted).
So it was back to the drawing board to re-draft the instructions and then re-write the clues. This was a somewhat surreal experience since the diagram words and “extra” words were largely the same but re-shuffled to give different combinations than those originally clued. Some weeks later, I submitted the revised puzzle and this time it was approved for publication.
My thanks are also due to John Green for his peerless effort and attention to detail in marking the entries and collating comments etc for the setter; to the editors, as above; and particularly to the solving fraternity for all the kind comments – and specifically to LWO for publishing these comments.