I have lost count on the number of times I have re-checked the wiring,
even leaving it to the next day didn't help.
I followed another thread from this forum
http://forum.lcdinfo.com/viewtopic.php?t=576&start=0&postdays=0&postorder=asc&highlight=
which looks to be the same as I have worked out.
I have noticed that although the lines across the display seem to be random, they apear to be the bottom most line of each character in text mode, and a Bitmap shows up as though lines are missing.
I am now thinking that the row generator chip T6A40 could be at fault.