Nigel, the converter (and interface) formerly hosted at folkinfo.org is now available at mandolintab.net. I trust it far more than the Concertina.net converter, which has a less flexible interface, was left to languish for many years without updates, and was glaringly misconfigured for guitar chords. Judging from comments above, most of these issues may now have been resolved, and the current maintainers may be making more commitment to keeping it up to rev. You can take your chances with it; I've given it up.

The mandolintab converter is free to use, requires no installation or user upgrading, and provides a sort of de facto portability standard, since everone can use it directly regardless of their own OS. The print output is very clean.