OK, some explanation...
The basic graph dates back to the early days of vectoring, and is found in a "Brodband Forum" document:
MR-257, though that link is to a newer "issue 2" of the document.
The graph applies to the UK to some extent, because it depicts profile 17a, with the theoretical top speed of 170Mbps.
However, it isn't fully appropriate...
- It is for 0.4mm cable, whereas the UK tends to be 0.5mm - at least in the D-side. As the footnotes in issue 2 say: the range of a particular speed can be increased by perhaps 4/3.
- It is for Annex A (US), not Annex B (EU).
- It almost certainly doesn't include any PSD masks for ADSL. That could maybe knock up to 8Mbps off the speeds.
- It makes no allowance for any of the bandwidth being used for FEC protection. The old DLM intervention settings would steal 10-15% of your speed for this.
- It makes no allowance for G.INP either.
As you can see, the gap between "perfect" and "almost absolute worst case" (the two triangles) is *huge*. Your line could be anywhere inbetween. However, the majority will be somewhere in the region of the blue crosses.
I used to have a line that was just over 16dB attenuation, with length around 375m. The current "A range" estimate is 59-78Mbps.
Using that "4/3" factor on the distance, I should be comparing with the set of results for 300m on that graph. It suggests a "single user" or "perfect vectoring" speed of 140Mbps, and a likely range "with crosstalk" of 60-100Mbps. If you lost 8Mbps (PSD mask) and 10% (DLM) from that, you could be somewhere under 50Mbps.