Henry Moore was a War Artist during the Second World War. He was inspired by seeing Londoners sheltering in the Underground Stations to avoid the air raids of the Blitz. He went down to observe and make quick sketches which he then worked up with watercolours later. The mixture of materials gave them an extra ordinary quality.
The mixed media technique was used in his other sketchbook work, layering watercolours, inks, oil pastels and chalks in his observational and thinking drawings
