seems good for areas I have tried - I note that some of the low speeds clocked are legacy products like 0.5 and 1M accounts that haven't been upgraded to MaxDSL or 21CN or have been kept on an obsolete profile.

This one now shows the true story of my postcode. More importantly that fibre has now be pulled from the rollout.

For my postcode, ST72LX, I get:

Postcode Postcode Status Any lines < 2 Mbps Average Speed Median Speed Maximum Speed Superfast Available
ST72LX OK No 16.8 Mbps 18.7 Mbps 23.2 Mbps Yes

However, as far as I know, superfast is not available. Our cabinet (8) is not upgraded and there are no plans that i have been able to identify. Virgin is also not available.

Is it possible to find out what the "yes" is based on?

Well good to see this information FINALLY updated!
My old post code:

One or more properties may be slower than 2 Mbps 7.6 Mbps 5.4 Mbps 14.7 Mbps No

And another one where I get 74/16 Mbit:

>= 30 Mbps 20 Mbps >= 30 Mbps

Thanks for the link, Andrew. Mostly ok for my P Code but the maximum speed is wildly optimistic!

The December 2011 data from Openreach gives
ST72LX ALSAGER FTTC, but not available yet 100% P8

So seems there is or at least was at one time plans to enable cabinet P8 which all the homes in the postcode are connected to.