I'd recommend this book for anyone who needs to write as part of their work - and that includes most of us!
It's packed full of simple writing tips to get you writing in plain English - but what I really liked was the debunking of the grammar myths. These are "rules" that you might remember from school or college (or heaven help you, a grammar book) that get in the way of writing clear, concise, conversational writing at work.
This is good value book and well worth the investment, not just for the grammatically perplexed but for anyone who wants to be a master of plain English.