Red printed over the previous blue layer. The red ink (T.N. Lawrence's scarlet) is very transparent. If you add white in an attempt to increase the opacity, the red turns to pink. I adding lots (nearly 50:50) of warm yellow ink, which increased the opacity without shifting the colour.
The lamp will have darker ink printed on it later, but I didn't want the red on those parts because I was worried that the slightest misregistration would show up too much. So I used a mask to hide these parts from the red on this layer.