Normally you wouldn’t give it a second glance. The sign is around three feet by two feet, perched above head height outside a pub on the A46 into Cheltenham.

It is well-produced, with letters neatly hand painted on to white board - evidently the work of a professional signwriter. But it’s the spelling that immediately draws the eye.

In large blue letters the sign invites you to “hold your garden fate or table top sale”. And it goes on to offer the service “free of charge to schools and charitties” (our italics).

The signwriting trade is not alone in perpetrating such atrocities.

Recently billboard posters went up around the London borough of Merton offering advice on building “extentions”. A leisure centre in Stroud is currently offering either bronze, silver or gold “catergory” of gym membership. And an advert in an expensive-looking glossy brochure listing advertising and marketing agencies has invented a new word “reck” to replace the traditionally spelt “wreck”.

Meanwhile the so-called “grocer’s apostrophe” which gives us potatoe’s and confuses “its” and “it’s”, continues to baffle not only grocers, but also graphic designers. A poster advertising a promotion for Burger King in Bristol recently urged cinemagoers to hold on to “you’re” used tickets.

What is going on? Is this a cunning marketing ploy using deliberate misspellings to attract attention? Like Toys “R” Us, or the Government’s use of the word Connexions to imply joined-up advice and guidance services for teenagers? Or is it simply poor literacy breaking through into our signs, hoardings and publications?

Sadly, it’s the latter, says Alan Wells, director of the Basic Skills Agency. “I think it is increasing - you certainly seem to see more examples of words poorly spelt in public signs.

“The other thing we get now is text-type spelling. I saw one the other day where someone had written ‘are’ as ‘r’, just a letter in a sentence. “I think the reason for that is that people have got used to texting. I never do that - when I text I text the whole word.”

Recent research for the new Concise Oxford English Dictionary also highlighted an epidemic of confused words that make their way into print.

Common examples include using “tow” instead of “toe” for “toe the line”, “loose” instead of “lose” and “draw” confused with “drawer”.

But how can a howler of a spelling mistake make it on to an advertising billboard, all the way through the production process, from copywriting to final printing? Helen Cornish of the International Society of Typographic Designers (ISTD) which represents graphic designers, says it’s down to a decline in the use of proofreading. She also says new technology and the rise of desktop publishing are partly to blame.

“People don’t check these days,” she says. “They rely on computers to do things for them. And people don’t care. They go around saying that spelling doesn’t really matter.

“Years ago you would be doing the paste-up on the desk yourself, and you would go and get the typesetting from the typesetter, who would have their own proof checkers looking at it before they sent it out. The chances were you would stop mistakes. But now people think ‘I’m a designer - I can do this’.”

The Society for Editors and Proofreaders (SfEP) represents more than 1,100 people in the publishing community, and as you would expect, is a staunch defender of correct punctuation and spelling.

It runs a range of accredited proofreading courses, and is planning to take its training out to companies which produce their own publications.

Spokeswoman Sara Hulse said companies are increasingly producing printed material in-house, and this is not checked properly. “If people employ proofreaders with qualifications such as the SfEP accreditation and registration, they will get a good job done,” she says.

She said the SfEP is constantly having to combat adverts in Sunday supplements saying things like “if you like reading, you could become a proofreader and earn pound;500 a week”.

“This is the sort of thing that makes people think proofreading is easy and anyone can do it. It’s not - you need a genuine aptitude for it.

“It is a skill that not many people have. Experienced proofreaders can transform poorly-written material, whether it be a road sign or a large academic textbook.”