Your neighbour has got about the same attenuation as I guessed for you.
However his line is performing well above par for some reason. I would have predicted 9 Meg rather than the 11.5 Meg that it is.
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 20 Meg WBC