Thanks for quick replies.... It's quite a high spec modern well built house. The alarm is to be sited in a walk in cupboard opposite the kitchen. It has a FSU straight from the CU. There is 10 cables in total around the house. For the life of me I couldn't find the last one. Then today I noticed just below the CU where the doorbell transformer is there was another cable in the wall, this just so happened to be the last alarm cable! I had spoken to the builder reference the last cable, however the spark that wired this place is no longer around to ask, hence why it's taken me so long to find the last cable.