You run the London marathon, you need a gimmick. For the past 22 years I have been writing the Guardian cryptic crossword under the pseudonym Paul, after my late brother, and I had already run four marathons in his memory. I realised there are about 26 clues in a puzzle, and 26 miles to a marathon. Suddenly the idea was there, and I began to regret it immediately.

I asked my crossword-setting colleague Richard Browne, AKA Imogen, to fill a grid with 26 words. Twenty-six crossword-loving volunteers were each allocated a mile, and a word. They were briefed to stand within yards of each milepost holding up their word, yelling “Crossword Paul!” to attract my attention as I passed. I then had until the next milepost to think of a suitable clue.

I also requested that the grid be filled with positive words: “SUFFER”, “PAIN” and, especially, “WALL” were to be avoided.

I am not designed for running; more for pizza and chocolate cake. Training hadn’t gone well, and I was dreading the thought of having to be creative every mile on top of the pain.

Although I practised spotting words while out on training runs, devising clues and recording them on my Apple Watch, there were problems on the day that I hadn’t anticipated. The sweat on the watch meant the touch sensitive screen failed over and over, and finding the “record” and “save” functions while running proved tricky.

But as usual, the London Marathon was a joy. The crowds make it. There’s no cynicism, no sense that the world is teetering on the edge of political, economical and ecological mayhem – all pulling together, moving in the same direction. That is, except for the man ahead of me, running the marathon backwards. I’m not sure if it was more shameful to be beaten by him, or the man carrying a fridge. Fortunately, for those who wish to solve the resulting puzzle, coming Saturday 6 May, the exasperated expletives punctuating my recorded efforts have been removed from the clues.

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