nazn wrote:
I would like to build a garden wall that will be adjoining my
neighbours front garden. As there has never been a wall here, how would
I go about measuring/drawing a line that accurately (and fairly) is
straight down the middle between our 2 properties. The wall will be
roughly 16 feet by around 4-5 foot high.

I have considered about using a laser pointing device, but am not too
sure how I would calibrate/level this to get a accurate reading. My
other plan would be to a make a square frame and align this outwards
from my rectangular bay window and then taking measurements between the
bay and the centre point between the two properties and then projecting
this measurement at the other end of the frame.

At the pavement end there is no post or markings where the centre line
is.
I would really appreaciate any advice if there was any other method
employed used to work this out, that was foolproof and could be
demonstrated to produce the same result every time in case of any
future issues.

Marking out is only part of the problem. Once you've agreed
it with your neighbour (including who owns the wall; will it
be built entirely on your ground), you've got to ensure that
it's safe (that's quite a high wall), and that you will not
get problems from the council, who may get ratty if it's over
a metre high next to the path.