Running on a mighty fixed 0.5Mbps service, and so happens I just speed tested it after upgrading my new router with an alternative open source firmware. Results were 499Kbps down and 234Kbps up.
Is a corporate service though and so the contention is very low, and I see very predictable speeds at all times.
I was fleetingly upgraded to a fixed 1Mbps service, but had no end of reliability problems. In the end BT told me my line wasn't up to it and said they'd downgrade it again for me. However, I then worked out the problem was actually being caused by my very old wireless gateway causing noise on the line. New wireless router fixed it, just in time for the downgrade to go through the day after. Waiting for the regrade back up to 1Mbps now. Sadly I can't go any faster since I'm so far from the exchange
.