So the other day I lowered the window (drivers window) to speak to
somebody and when pressing the button to raise it, it rose to the top
and this horrendous banging noise came from inside the door - i
thought i was under attack by some heavy artillery!!

If i release the switch it stops so the problem is obviously that it
can't sense the window has been closed and still tries to close it,
thus the knocking sound! I am thinking the regulator needs to be
replaced (I found a link that explains how to do it) but am hoping
that I can get away with just buying a new window switch because
replacing the regulator will be a doozy. Was thinking that I could
remove the passenger window switch and hook it up to the driver side
window and see if it works to determine if its the switch that is bad.
What are your thoughts?

(window regulator link)
http://www.landrovergeeks.com/repair...ange-rover-p38

 

It is the regulator. Tear it apart. You might get lucky and be able to repair it.