So many different websites say 70Mb, Google says 96Mb, BT Wholesale Broadband Performance Test says 136Mb.
Probably a better question is what contention ratio is ultrafast fibre by BT supplied at?
I know adsl suppliers that varied in their ratios. Some better than others.
The BT Wholesale checker is measuring speed wholly within the BT Network and thus gives a reliable speedtest of the portion of the network under the control of BT. Once your connection leaves the BT network the speed is beyond BT's control and could be traversing any old piece of wet string.