'How to build a two valve set': No 2, Godfrey Philips cigarette card, 1925.
© Science Museum / Science & Society Picture Library
The reverse of the card reads: 'The panel is of ebonite 1/4 inch thick and measures 14 in x 7 in. It may be bought from any radio store and it would be advisable for those who do not poses suitable drills to have the 10 holes drilled at the shop while making the purchase. The positions of the holes will depend to a certain extent on the components used. The sizes and positions indicated are suitable for the components recommended.'