I've come across that as well. When some ATCs want to get rid of you because you're outside their area then they sometimes suggest London Information as the next frequency (probably because they haven't got a better one for you to call). I usually ignore them and if I can't find a better frequency I'll put it on 121.5 - just in case of an emergency.
I agree with Chilli, you should only use it if you actually want some information. Perhaps they should start explicitly asking 'What information do you require?'. That'll get some interesting responses!
How does London Information work? There are several different frequencies; is each frequency controller by a separate person or are they all ganged together?