My neighbours get around the same speed so it's down to the copper and crosstalk guess.

I used to get around 33 Mbps but that was because my line was originally connected to a temporary cable that was put in for the site and sales offices which was some something like 400m shorter. That has since been removed and any lines connected to it were moved the cable that comes into the estate from the next road up.

That copper is obviously very thin and poor then.

Or it could be that the line conditions have not changed so that the sync is virtually the same.

A sync virtually the same is not a 100% proof of banding, it might suggest its presence - which is what I am trying to get across.

No, it most likely takes a longer route than the original temporary site office feed.

It is extremely unlikely that different gauge copper has been used. From what the poster says this sounds like a recently built site ... Openreach have basically only used 0.5 gauge copper for its new D side cables for well over 10 years.

It is a new site completed started in 2014 and completed earlier this year. The temporary cable literally just came onto my road and terminated in a chamber 20m away from my house whereas the cable for Phase 1 of the development runs past the end of my road and along the next road up before coming down onto the Phase 2 houses and terminates in the same chamber.

You could say it literally goes round the houses.