UK Car Repair: jaguar xj6, light fuse, 1993 jaguar xj6

Question
have a 1993 jaguar xj6. recently have problems with battery draining at random. have had battery checked. it is okay. sometimes car starts right up. sometimes I drive it for hours, cut it off, and will not start back up.....completely dead. mechanic thinks it might be a problem with electrial system caused by security system. would removing fuse for security system help? If so can you please tell me what fuse it is and which fuse box it is in?

Answer
No, removing the fuse would not help the alarm is made to be "tamper" resistent. But if the battery is draining, any mechanic could remove the fuses one at a time until the drain disappears.  You need a test light, disconnect the earth cable and connect the light between the cable and the terminal.  Remove the interior light fuse first. Presumably the test light is on! Now start removing fuses until it goes out, that is the circuit causing the problem.