Let's Hear It For Copy-Editors.

The copy-edited ms of Devil's Garden, my new book, arrived this week so I've been head-down for the last few days.

Usually the copy-editing is a straightforward matter – I just work through to the comments, change if I think it's necessary, explain why I'm not going to change if not. There are usually only a handful anyway – and I'm particularly grateful when they pick up on the fact that I have somehow not noticed using the same word three times in as many lines or contradicted what I had said in Chapter Two when I reached Chapter Eleven.

This time I was surprised and not a little dismayed when there were three pages of queries as well, nearly all of them relating to a time problem, where they couldn't work out what day it was meant to be – the evidence was contradictory.

Most of my books have a tight time schedule, and in this one the whole action unfolds in the course of a week, on the basis of real time, so trying to unpick it all looked as if it was going to be a major nightmare to sort out.

My copy-editors had meticulously gone through the whole book, quoting and highlighting phrases where the time was mentioned. I hate to think how long it must have taken and when I got down to studying the comments I could see why it was a problem.

Then I started working through the book and I realised the whole thing had stemmed from one word. I remembered considering whether the junior detective should arrive on the scene on the Monday or on the Tuesday. I'd thought at first it should be Monday but then as I wrote on the action dictated a Tuesday arrival and somehow in the revision I didn't notice what I'd done.

With the change in that one word, it all worked, with only a very few minor tweaks of the 'last night' when it should be 'two nights ago' variety. (At least I hope it has – they'll be checking it next week!)

When I was small and learning to knit I would get it into a bit of a mess and take it to my grandma. She would painstakingly rip a bit back, pick up the dropped stitches and give it back to me – sorted.

That's what copy-editors do. I'd like to say a great big thank you to mine, and a great big apology too, for giving them so much trouble by my carelessness.