Since then I have done speed tests at Think Broadband and speedtest.net
Today at thinkbroadband.com I got a download rewarding of 20.8 Mbps whereas at speedtest.net (which BT uses) I got 37Mbps.
How can these tests vary so much in the space of a minute?
BT Infinity 35Mbps
using BT Home Hub 3 and Openreach VDSL modem
formerly on O2 Premium, Be Unlimited, Zen 8000 Active