Very often when artists paint or draw something different from the norm they suddenly
think "How can I draw that".  This drawing  had about 3 days of work done to it.  First the
overall sketch was drawn and then the fine detail applied working from the top down.
When Brian reached the footbridge he realised that he could not draw the squares of the mesh on the bridge as it would look wrong. Not wishing to destroy 3 days work he
tried various methods.  The result was that he drew nothing of the mesh but merely drew what was behind it!!  It was the reason for him to name it "The Footbridge".