The colour frontispiece of Fivepenny Mystery. There were three editions of the Penny books:
1. The original Nelson books, lavishly illustrated with colour frontispieces and high quality paper;
2. The Britannic Series, also with colour frontispieces and many illustrations on high quality paper;
3. The Triumph Series, with a black and white frontis and illustrations but printed on cheaper paper that tends to tan more quickly.
I have no first editions. My Penny Foolish, Fourpenny Fair and Crooked Sixpence are Britannic books, and the others are Triumph editions.
I would like to thank Elizabeth Lindsay for providing the scanned frontispiece.