The Language Wars: A History of Proper English. As his near-namesake in Pymalion/My Fair Lady points out, when one Englishman opens his mouth it sure to offend another one.
Like David Crystal, Hitchings takes a relaxed view regarding the alleged decline in standard. He points out that bitter protests about the misuse of English have been a running theme since the 18th century. And the impact of texting on the writing habits of young people has been wildly exaggerated. Teenagers know that it's not wise 4u2 put emoticons in your job application letter.
Nonetheless, it is striking is how the range of widely used formal vocabulary has narrowed dramatically in recent years. To take just one example, only a small minority recognise biblical references which would have been universally familiar fifty years ago. While it's true that the internet and other new spheres of activity have introduced new words and concepts, I sense that this does not fully compensate for what has been lost.