Yes it has been seen lots recently. It means the test is broken. Those speeds are not possible with the technology used.
The Think Broadband speed test is much more detailed, reliable and accurate.

Or it means something is interfering with the test on the client - like a virus checker screwing things up.

Or Firefox is broken.

Again.

And why we record the graphs so if people have issues they can link to one of our tests and all can see the pattern and as has been done in the past, defensive programming can sometimes mitigate browser specific quirks.

The BT Wholesale speed test has never been reliable and is only something I recommend for those on ADSL2+ seeking to learn their IP Profile setting.

Update:

Lost dial tone today. Phone Dead. BB still good 73/18

I deduce that there must be a fault between FTTC Cab and Exchange.

Question: Can an intermittent "copper" fault between FTTC Cab and Exchange sometimes cause a Fibre BB fault in the Cab e.g. a short in the copper wires shorts the DLAM or something similar?

PS Its been very wet again!

https://www.thinkbroadband.com/speedtest/15185994727...

BTW - As said previously, in tests I have been using both MS Edge and Chrome browsers to rule out browser specific issues.

Your speed test today shows that there is not broadband fault, you would not be getting 74 Mbps download if there was a fault

So what you have is a voice fault, and time to phone who pay voice line rental to and report that.

Dial tone is back intermittently.

Rang landline from mobile again just now, I could receive the call but there was no ring - wired phone in master, cordless disconnected.

Report the voice fault rather than telling us about it

Andrew - I know I have no BB fault ATM , but was posing the question to try to account for the previous bizarre fault.