Thank you EarlyMon, your offer is much appreciated and I may well take you up on it at some point in the future. I'm content to continue with using Google maps for navigation, and Route 66 for offline route checking (with the option of monthly or annual navigation license if necessary). As you point out, I suspect that even if I were able to load Locations onto my One it wouldn't run properly with Sense 5.0, and I certainly don't want to cause any sort of conflict on the One.
More to the point I'd have a hell of a job getting the Desire S in my hands long enough to do anything more than switch it on!!!