1. A method of controlling access to a data processor, the data processor being arranged to execute a plurality of requested function commands, the method comprising: determining from previously executed function commands a set of parameters that reflect a pattern or operation of the data processor by a user; determining whether a requested function command conforms to a permission set of the user; in response to the requested function command being determined to conform to the permission set, using the set of parameters to determine whether the requested function command conforms with the pattern of operation of the data processor; in response to determining that the requested function command does not conform to the pattern of operation of the data processor, controlling the data processor to halt the execution of the requested function command; and controlling the data processor to subsequently resume execution of the requested function command in response to one or more resumption conditions being satisfied.