This article on the UK Design Museum site tells the story of the British motorway and general road signage system, designed by Jock Kinneir and Margaret Calvert. It begins:
Determined to illustrate the haphazard state of British road signage at the turn of the 1960s, the graphic designer Herbert Spencer drove from central London to the recently opened Heathrow London Airport and photographed each of the road signs that he came across along the way.
Perhaps it is time for someone to do something similar for the drive from Naas via the M50 ring-road to the Airport. It would certainly be an interesting project to do over a few Sunday mornings.