I did something
vaguely similar - two young German girls were on the tube, and asked me how to get to canary wharf. They looked to be about 14 or 15, this was maybe 6.30pm, in rush hour London

First problem was that they were travelling in entirely the wrong direction on the wrong line, and second was that it was a bit of a complicated route from where we were. Third problem was they hardly spoke English, and I can just about order a beer in German, but nothing else.

I tried to show them how to get to Canary wharf, with the tube map in the train, but I could see they were confused, and both getting a bit panicky.

So, with lots of pointing, beckoning and 'this way'ing, I took them to Canary wharf myself. They only realised what I was doing when we actually got there.

This was totally the opposite direction to where I was going, made a 45 minute journey into an hour and a half, but I'd like to think if it was my kids, someone would do the same.
(username failed moderation, Mon 13 Feb 2012, 16:45, Reply)