1. Data processing apparatus for generating an alarm based on the output of at least one camera, comprising: a video data receiver configured to receive video data; and an alarm engine configured to perform sequential analysis of said received video data to determine a sequence of at least one incident and to generate an alarm signal the video data corresponds to at least one configuration file in the alarm engine; the data processing apparatus including a graphical user interface (GUI) for generating the at least one configuration file, which is operable: (i) to accept user input to generate a plurality of incident analysis functions representing incidents that may be present in the video data, and to display the incident analysis functions so generated; (ii) to accept user input to generate a plurality of contemporaneous analysis functions that define operations that are performed on at least one incident analysis output signal based on Boolean logic, and to display the contemporaneous analysis functions so generated; and (iii) to accept user input to generate a plurality of sequential analysis functions that define operations that are performed on at least one of the contemporaneous analysis functions occurring sequentially based on Boolean logic, and to display the sequential analysis functions so generated.