What 'line' is she talking about?

I did my presentation this morning -I think it went ok- but Laura's wasn't until this afternoon and, as you have to stay until everyone on your course has done theirs, I had a few hours to kill before getting the train home.

So I had a wander around Greenwich Park and up to the Royal Observatory.
That's where this crazy lady was giving some kind of performance, going on about somebody moving her line. I assume she was taking about the Greenwich Meridian line and I think she may have supposedly come on o time machine...she did seem to be keeping the kids entertained I suppose.
I can't help but think that she must have been a bit hot in that get up though.