In the new Grade 5 theory workbook, on page 28, the example given in Ex. 2 on intervals, the interval from D flat to A is described as "Diminished". Shouldn't it be "Augmented"?

Yes Dflat to A is an Augmented fifth if it's the bottom note that's the Dflat.

Thank you for verifying that! I was really surprised when I was teaching a student tonight and was going over the answer with her, only to find that my analysis of the interval disagreed with the printed answer in the workbook. Very much appreciate the time you took to confirm the interval is augmented, for the D flat is indeed the bottom note.

My copy correctly says Augmented 5th - maybe they've done a reprint correcting this?

You are absolutely right! I have a supply of theory workbooks of various grades here at home, and I have just had a look at two of the most most recently published Grade 5 workbooks. To my enormous surprise the interval example on page 28, exercise 2, is identified as an "Augmented 5th" in bright pink! Well, well, well!

And there I was, getting all twitched up yesterday, thinking I couldn't identify an interval properly any more because I was sure it was an augmented 5th, not the diminished 5th the workbook said it was.

Thank you so much for your reply. You have done a lot for my own feelings of self-worth in knowing my augmented intervals from my diminished ones.