I know that Virgin media usually takes a flogging round these parts, but when I was living in Belfast I had their 150 Mbit fibre (no telly or phone, just the internet) and it was very fast.
Now 150 Mbit is supposed to be just under 19 Mbyte per second however I regularly got speeds of 25 - 30 Mbyte on downloads so I'm guessing that when the line is uncongested that Virgin happily upped the speeds to 300 ish Mbit.
Any time my speed was slow I can pretty much guarantee that it was due to the site I was connected to and not my line.
Now, in Japan on a 100 Mbit connection it is frustrating as hell, it crawls in comparison. I wish I had my old Virgin fibre line back. :-(