In typography, a fat face letterform is a serif typeface or piece of lettering in the Didone or modern style with an extremely bold design. Fat face typefaces appeared in London around 1805–1810 and became widely popular; John Lewis describes the fat face as "the first real display typeface." While decorated typefaces and lettering styles existed in the past, for instance inline and shadowed forms, the fat faces' extreme design and their issue in very large poster sizes had an immediate impact on display typography in the early nineteenth century. Historian James Mosley describes a fat face as "designed like a naval broadside to sock its commercial message...by sheer aggressive weight of heavy metal." and that (unlike slab serif typefaces) "while the thick lines were very thick, the thin ones remained the same - or in proportion, very thin indeed." The same style of letters was also widely used executed as custom lettering rather than as a typeface in the nineteenth century, in architecture, on tombstones and on signage. Versions were executed as roman or upright, italics and with designs inside the main bold strokes of the letter, such as a white line, patterns or decorations such as fruits or flowers. They are different in style to the slab serif typefaces which appeared shortly afterwards, in which the serifs themselves are also made bold in weight. Great changes took place in the style of printed letters available from type foundries in the hundred years after 1750. At the beginning of this period, fonts in Latin-alphabet printing were predominantly intended for book printing. The modern concept of text faces having companion bold fonts did not exist, although some titling capitals were quite bold; if a bolder effect was intended blackletter might be used. From the arrival of roman type around 1475 to the late eighteenth century, relatively little development in letter design took place, as most fonts of the period were intended for body text, and they stayed relatively similar in design, generally ignoring local styles of lettering or newer "pointed-pen" styles of calligraphy.