It was the Orisec covert wire free shocks, we had new ones delivered today.
One of our engineers has them on his work load for this afternoon.
The original ones were fine unless fitted to a door jam or close to a wall, even when set up for concrete they just would not trip (the theory is the harder the surface the less shock needed to trip them) we have been installing these for a while but the new standards had made it hard for us to convince the customer that they were OK.
Orisec have added a further 2 settings to cover our needs, I'll let you know how they are.