Originally Posted by vaughant

Almost certain they do have an alarm at that age.

Another thing to check is that there's no water getting into the fusebox which is behind the glovebox on the passenger side,I've seen this on one or two of these and that could be causing havoc.

Usually caused by a badly sealed windscreen.

I'm going with the lads above on an alarm/immobiliser system issue.
After all the indicators flash everytime you lock/unlock it anyway.