Thank you Robert, an incredibly rapid response and just what the doctor ordered as it were.
I do not know whether you or anyone else can answer this supplementary question but the 'nutshell' page indicates that the distance (for direct line of sight) is quote "1,90m minimum from the edge of the window (outside face of the wall)". A quick measure indicates there is a distance of around 1,90 m but this is measuring from the edge of the house to a sloping earth bank with no clear indication of the exact boundary line. To further confuse, the proposed window would be recessed into the wall by around 60cm so is it the edge of the wall (where most windows would be) or is it where the window would be sited?
I appreciate that the people responsible for the plan cadestral will provide the exact position of the boundary and that it will be best to discuss this with my neighbour first. What I am really trying to get is the best briefing I can before approaching him.