If I run the BT wholesale speed checker I get:
Download speed achieved during the test was - 38.31 Mbps
For your connection, the acceptable range of speeds is 36.97 Mbps-52.81 Mbps .
IP Profile for your line is - 52.81 Mbps
Upload speed achieved during the test was - 8.04Mbps
Upstream Rate IP profile on your line is - 20 Mbps
However if I run the TBB speed test, I get:
Avg TBBx1 download 50.28Mbs Avg HTPx6 download 37.20
Avg TBB upload 8.47Mbs
So which is right - am I getting 50 down or 37?