Hi Cubit,
Thanks for the reply. I guess I was concerned that if the LED's flash all the time, then it may signal a potential intruder that the system is dummy, as it could represent a 'live' system, even if the property is clearly occupied.
Given you have confirmed that LED's must always flash, then that is fine. All new systems going in now will have to follow this regulation.
Out of interest, can there be no LED's flashing, and then just the strobe when set off?