There are only 2 figures that can be obtained, sync rate and download or throughput rate. The sync rate is the speed of the DSL signal to your hub which is obtained from the Hub stats page and is purely a measure of the rate between the cabinet and the Hub. The download rate is the rate an individual device receives from a distant server and will always be slower than the sync rate due to protocol overheads. It will also be susceptible to the vagaries of the wider internet and any problems of congestion.
OK, by ignoring the incorrect phone number being offered by the BT performance test the test ran for two minutes and came back with 70.0 Mbps. I'm satisfied that this a true test reflecting actual conditions at the time of the test rather than the static rates being reported in the technical log.
Thanks guys.