Official documents, which since the Norman Conquest had generally been written in French, began to appear in English from about 1430.[15] From here on the Chancery Standard of written English begins to emerge – based, like Chaucer's work, on the East Midlands-influenced London speech. The clerks who used this standard would have been familiar with French and Latin, which probably influenced the forms they chose. By the mid-15th century, Chancery Standard was used for most official purposes except by the Church, which still used Latin, and for some legal purposes, for which Law French and some Latin were used. It was disseminated around England by bureaucrats on official business and slowly gained prestige.[16]