Thanks all.
The bike is a 2000 model Tiger 855i which has the alarm going off all the time. Even if the alarm wasn't faulty, I would remove it as I hate alarms on bikes.
A bypass plug has been ordered from a Triumph dealer now and should be with today or tomorrow. I just called the dealer that fitted the alarm 10 years ago and explained the problem. £3.69 for the loopback / bypass plug. Bargain. I bet the FZS600 one would be a bit more.