For us aeros people, it's nice to hear about other traffic on our home frequency as we're often poling around somewhere close to base. I usually let my home field know when/where/how I'll be playing, so if you dialled up in transit you'd find out about me and vice versa.
As for London information, last time I spoke to them I was sat at their desk in Swanwick. But then again my flying is very one-dimensional, in a very three dimensional kind of way :-)
(Reminds me, must see if I can sort out another visit...)