Dark purple 3G
Light Purple
crappier "most slow" edge connection.
IIRC it is an O2 provisioned service. So pretty much if an O2 moby works then your kindle will work.
Look here:
http://client0.cellmaps.com/viewer.html?cov=2&view=intl
you said UK. Obviously you would be better getting a look at the realtime as indicated by this link above.
These snaps best serve as an historical reference for *IF* cellmaps.com should prove unavailable