I used this last year and it seemed to work well. As I was using the GPS beacon on my phone I saved battery by not having it sending out locations at set times but did an ad-hoc "here I am" at varying times so control could see progress. Not sure what information is displayed but if it is just initial & surname then does not reveal the gender of the walker or whether others are in the group, so that may go some way to addressing Vanessa's concerns

I almost abandoned the registration due to the mention of twitter, but as Alan says it is only needed to sign up. I have had the occasional email to say I haven't completed my twitter account confirmation but I just ignore these.

Have a good crossing folks and I look forward to seeing your progress