All now working - Alarm was installed in the year 2013. In the event of fire, break in or panic alarm, the dialler rings three different numbers in order to acknowledge the call while the alarm is sounding. Seems quite alright to me - don't want to splash out on upgrading!
Just one issue now is that the Foreign Electromotive Forces Test has a Fail!
Test Verdict: FAIL
AC Vrg = 3, Vtg = 0, Vtr = 0
DC Vrg = -8028mV, Vtg = 394mV, Vtr = 8422mV

All other tests pass so not sure what the issue is here.