Six Across

Corvid's crosswords are famously unkind on a Thursday.

This is a matter of record. There is a website that tracks average solve times by setter, and Corvid sits at the wrong end of it, and has done since 1994, and takes an unattractive amount of pride in this.

His real name is Gerald Fitch and he is seventy-four and he sets in the back bedroom on a board his wife made him in 1988 because he kept using the dining table.

The rules of the trade are simple and he has never broken them. The clue must be fair. The surface reading should mislead. And the solver, on getting it, should be annoyed at themselves rather than at you — that is the whole art, and it is the reason most people cannot do this.

Every Thursday for thirty-one years.

He has a postbag. Setters do. Most of it is people pointing out errors, of which he has made eleven, all of which he remembers.

And then there is M.

M first wrote in 1996 about 14 down, which was a bad clue, and which M dismantled in four lines with such precision that Gerald wrote back — setters do not write back — to say so.

M wrote again the following month. And the month after.

For twenty-nine years.

Never an address. A postbox number, and then later an email that was three letters and a provider. Never a first name; never anything about a job or a town or a life. Gerald knows M does the puzzle on Thursday evenings, takes between forty minutes and two hours, and has never once failed to finish.

Nobody else has ever finished all of them. He checks. There is a forum; he lurks on it shamefully.

They have argued about anagram indicators. They have had a two-year disagreement about whether "almost" can shorten a word from the front. M thinks it can. M is wrong, and has been wrong for two years, with enormous style.

In 2011 Gerald had a bad year and set a puzzle that was, he knew as he sent it, not good enough. M's letter that week did not mention the puzzle at all. It said: Off week. They happen. Same time next Thursday.

He has that one.

Last month the letters stopped.

Four Thursdays. Gerald told himself: holiday. Then: illness. Then he made himself stop telling himself things.

On the fifth Thursday an envelope came in unfamiliar handwriting.

Dear Mr Fitch — you don't know me, I'm Marguerite's daughter. She passed in March. I'm sorry to be so long telling you; I only found your letters last week when I did the desk.

She kept every one. Thirty-one of your puzzles are in the drawer with them, the ones she said were your best, and there's a note on top of those in her writing that says CORVID — THE GOOD ONES, which I think you'd have liked.

I have to tell you something. She never finished them.

She had a stroke in 1995, the year before she started writing to you, and after it she couldn't hold the grid in her head. She could do a clue — she could do any single clue, she was brilliant at it to the end — but she couldn't do the whole. It went out of her.

So she'd take one clue a week. Just one. She'd work at it for as long as it took, sometimes days, and then she'd write to you about it as if she'd done the lot. She said you'd stop writing back if you knew.

She was ninety-one. She did your puzzle on Thursday for twenty-nine years.

Gerald sat in the back bedroom at the board his wife made him.

Twenty-nine years of the only solver who never missed one. One clue a week. Six across, or fourteen down, or whatever it was — chosen carefully, he realised, from the four or five that mattered, because she had always known which ones mattered.

He thought: she'd have finished them. If it had stayed in her, she'd have finished every one.

Then he thought, more slowly: she did.

He set Thursday's puzzle that evening. It is not one of his hard ones. There is a word running down the left-hand side that nobody has commented on and probably nobody will.

He would rather they didn't.