The peeping alarm on the substation beneath Breton House has now been fixed. Here are some notes from the story taken from
this thread on Barbican Talk:
The alarm started sounding on Saturday 19th Dec.
The alarm was on the power substation so the first port of call was UK Power on 0800 096 9960 (note: the substation's reference number is 42066). UK Power engineers visited a few times over the weekend and concluded that the problem was with the alarm battery, but in the end concluded that it was not their alarm nor their battery. The alarm is for the halon gas alarm for the substation which is apparently not the responsibility of UK Power Networks.
The estate engineer was contacted next (24/7 help desk on 02073827222). He could not get through the locked gate to reach the alarm, which was unfortunate because there is a simple re-set button that simply needs to be pressed, until such time as the alarm is fixed.
The estate engineer said that the alarm is apparently the responsibility of the barbican centre and they had to wait for the fire alarm company, Global, to come out.
While waiting for Global the CPAs were able to get access to the alarm and used the reset button to silence it from time to time.
No more peeping heard from the evening of 23rd. Presumably Global have fixed it.