From the ancient cave paintings at Lascaux to the medieval Mappa Mundi, history shows that humankind has always had an affinity with the pictorial representation of information.

Even though these examples had not yet quite evolved into data visualization, many people are still surprised to learn just how early the graphs and charts we might recognise today came into existence.

William Playfair, the Scots engineer and economist was something of a colourful individual. The combination of his early engineering training and rather unconventional character proved to be a fertile environment for his innovative methods of conveying ideas. Even though there was limited uptake by the scientific community at the time, Playfair argued that charts communicated better than tables of data. Following on from Priestley’s time line and James Watt’s steam measuring dial, he singlehandedly invented the line graph, the bar chart and the pie chart in the years between 1786 and 1801; and his work is considered to be the foundation of all modern data visualization. The line graph on the right; shows a chart Playfair designed to illustrate the growing problem of national debt in late 18th century Britain. Somethings never change!

An early example of data visualization being employed in direct support of decision making can be found in use at Hillingdon House  in West London during the summer of 1940. This was the headquarters of Number 11 Group, Royal Air Force Fighter Command during the Battle of Britain and nerve centre of the Dowding System. Air Chief Marshall Sir Hugh Dowding, the Head of Fighter Command, had prepared for the threat of invasion by developing the world’s first early warning air defence system.

Inputs came in from traditional intelligence reports, the observer corps and the newly introduced technology of radar. These data were fed directly to Bentley Priory and the details of inbound aircraft types, numbers, heights and speeds were mapped on a huge plotting table.

This information together with the “tote board” that showed the numbers and state of readiness of the RAF fighter squadrons, allowed the controllers who were located on a balcony above the plotting table to make split second decisions regarding the deployment of defensive aircraft. Because the Luftwaffe had twice as many fighter planes as the RAF, the speed of decision making was essential in order to gain every possible advantage.

At an extremely dramatic point in history, Dowding had not only seen the need for intelligence gathering, but had recognised that a special method was required to interpret it. Through the use of charts, colour and movement, data that had originated from a variety of different sources could be plotted in such a way as to present insight that was both simple and clear enough for the controllers to make critical decisions in a matter of seconds.  While the techniques may appear labour intensive and somewhat rudimentary by today’s standards, you’d be hard pressed to find a better example of the power of data visualization.