"About twelve months ago I placed a classified ad in a national magazine for my website, English Banana.com. A member of the classified team took the wording I wanted over the phone and agreed to design the ad, using my site's logo, copied from the website. The wording I asked for was:

"The ad cost almost £100, but I was happy to pay because of the exposure I believed it would bring to my website. When I bought a copy of the finished magazine I was initially pleased with the layout of the ad but then horrified by the spelling mistake. The wording read:

"Apart from the unnecessary capital letter on 'Available', the misspelled 'photocopyable' jumped out at me from the page. Since I had already paid for the ad there was nothing I could do. What would you have felt like doing, if you had paid £100 for the ad? When I phoned up to find out what had happened the classified ads manager was blasé about the error. He said, 'Does it really make that much of a difference?' I asked for a discount on the next ad and he started to haggle, saying, 'What's the price of an 'i' or a 'y'?' What he meant, I suppose, was how could you quantify what a mistake like that was worth? I explained that my website is aimed at people learning English and that its reputation and authority as a teaching tool could be damaged by an ad that showed that we ourselves have problems with spelling. It is human nature that a reader would probably attribute the mistake of 'photocopyable' to the company which the ad represents, despite the fault lying with the ad designer. In the end he gave me a discount of £25 on the next ad, which didn't run, because a few weeks later I had the chance to cancel it. I have not advertised in that esteemed organ since, which means that they have lost a trade customer due to a 'y' instead of an 'i'. The classified ads manager raised a good question, though. Does it really make that much of a difference?

"It seems that almost everyone has read The Da Vinci Code by Dan Brown. But would you have picked up the book – let alone bought it – if the title on the cover had been spelled The Da Vinci Cod? Even though the entire contents of the book may have been mistake-free in terms of spelling and grammar, the misspelled title on the cover would have put off the majority of people from buying it. Why? Because it's wrong. Everyone knows that the correct title is The Da Vinci Code. There is general agreement about the spelling of the word 'Code'.

"If the title wasn't spelled right, how could you be sure that the rest of the book wasn't also full of mistakes? We need to have confidence that what we are reading is right. We all make mistakes when writing English. Some of them can be spotted if we take time to check our work. Other mistakes are made because our spelling skills need improving or there is a lack of understanding about certain areas of use in grammar; for example when and how to use a comma.

"All of the examples in this book are adapted from actual examples of English that I have spotted during the past twelve months. This is English as written by people who speak and write English as their first language (and, no doubt in many cases, their only language). Educated people. People who have, in most cases, enjoyed as many as sixteen years of full-time education. People who have been to university and graduated with first- and second-class degrees. People who have achieved high-paying jobs in advertising and marketing without ever really fully understanding the possessive role of the apostrophe..."