This item of mid 1920s Mullard advertising was printed on thick cardboard and was aimed at point of sale advertising.
She was seen at the National Vintage Communications Fair in 2016 but was priced above the museum's budget - I had spent all my cash when I saw her. I rushed to get extra cash but she had been sold when I returned. Fortunately I had my phone with me when I first saw her and took a picture with the board on the floor of the exhibition hall.
The young lady was in fair condition considering she was over 90 years old but time had damaged her. Photoshop to the rescue - just a little.
The style of the valve in the image matches the Mullard valves of 1924. The lettering on the base of the advertising picture does not seem to match any of the valves produced.