I hadn't actually considered Algorithm::Diff as I had assumed it to be line oriented. A brief scan of the docs show that the basic detection method employed is Longest Common Sequence, which isn't really applicable to my problem.

I've also looked at String::Approx, Text::Levenshtien and Text::Soundex, but again, these aren't geared to detecting a single transposition. They are also incredibly slow if you are trying to do this on thousands of strings.

I've also coded a simple looping comparison, and played with XOR, but I didn't want to influence the ideas. I have a vague memory of there being a clever way of doing this, but searching the web didn't elicite anything from the vague memory I have.

So, I thought I'd ask:)