Datamining is about discovering patterns in text, but the Old Bailey Proceedings already incorporates tagged data reflecting what contemporaries thought they were doing.  The  nature of the crime, the name, gender and age of the defendant, the verdict and  punishment were described in words their authors thought beyond  mis-interpretation.  To use datamining to find new patterns, it would  help if we could subtract the patterns that we already know about.   The  huge rise in theft prosecutions in the first half of the nineteenth  century, the changing proportion of men and women prosecuted, the  evolving nature of the crime itself; each needs to be interrogated to  illustrate where changes in language can be explained as the result of  changing judicial practise, and where these changes suggest a new and different  explanation.