Another year, another ISP. This time around we’ve chosen BT’s 50Mbps download / 9Mbps upload plan as that is the fastest available at this address.
This is an FTTC connection that is throttled by BT. The connection speed peaks at 120Mbps for a split-second before rapidly descending to precisely 50Mbps.
I configured the server to run a internet speed test daily at 2:30am, and you can see a graph of the results below:

It turned out that my speedtest program was inaccurate and all the times that it reported ~2.5 Mbps upload it actually meant 9 Mbps. It was a very strange bug indeed. Somewhere around April/May I switched to the newly launched official Ookla Speedtest CLI for more accurate results.
Maximum (Mbps) | Minimum (Mbps) | Average (Mbps) | |
Download | 51.48 | 28.26 | 50.0 |
Upload | 9.56 | 2.47 | 5.2 |
Ping | 115.8 | 5.5 | 11.3 |
Ignoring the occasional dips, performance was solid throughout the year and I did not experience any major issues with BT. If they offered their 76Mbps download / 18Mbps upload plan at this address, they would certainly be a recommendable choice.
Edit 01/07/2020:
Switched to Vodafone as an ISP, on their 76Mbps download / 18Mbps upload plan.