Just to clarify, I used a BT Smart Hub - Type A to test the steps above. I intend to use the hub in bridge mode (ie as a modem only) and pass through the connection to my own firewall/router.
All that the post by @technononsense is saying, is that that option also exists on the normal residential hub, except that its not on the menu, you have to access it by changing the url.
The post doesn't actually specify whether it is the home hub or the business hub 6 which has had the menu option removed.
The subsequent post on this thread now does.
The new Zyxel XMG3927-50A router is G.Fast & is very good, I'm using one on BT Ultrafast 330. Unfortunately, at the time of writing, the current firmware isn't BT enabled so the auto setup wizard fails to detect the BT service. However there are only a couple of settings you need to input manually to get it working. The main UK supplier has been out of stock for a while now so I got mine from a German dealer, cost about £150 & comes with both UK & EU mains plugs.