Having attended not one, but three launches of Watercolour World yesterday, I learned a great deal more about how widespread its use was as a medium of documentary record.

The first was the extent to which its use was pioneered by the army in the 1740s, following Thomas Sandby’s appointment as private secretary and draughtsman to the Duke of Cumberland, who took him with him to record the Battle of Dettingen and made records of the enemy encampments at the Battle of Culloden. In the late eighteenth century, it was regarded as a useful skill in the arsenal of an army officer, making it possible to document and survey military fortifications.

The next key development was the establishment of the Whatman paper milk in Maidstone in 1740 which led to the production of good quality wove paper in 1756.

The third key development was the invention of the paint cake in 1781 by William and Thomas Reeves, which made it possible for amateurs and professionals to go out into the world with a box of watercolours in their pocket to record the appearance of volcanoes and balloons and all other forms of natural phenomena.