Nope, I don't think an alarm was even a factory option. Those that were fitted from new were likely done by the dealer (Or farmed out to a local alarm retailer) and so depending on where the car was purchased it could have any old alarm.
Then of course you have 16+ years of ownership where people will have had one fitted by clifford, toad etc. The insurance company will want the certificate that came with the alarm when it was fitted. If it's not in your history folder then you'll probably need to fit a new one to get any discount on your insurance.
Nick