Thanks to all for your assistance. The problem has been resolved. I followed the instructions below and Tamper fault went away. I did however had to extend the door tamper spring slightly to ensure good connection when closed.
"This is a common problem, normally if you open control panel (2 screws) remove mains and battery (External bell should ring). After 20 sec reconnect mains and battery and stop int sounder using your code. Replace lid and screws enter your code again to clear the tamper indication.System should now be OK. You must be aware that if this does not work you may require an eng. 9448 has two tamper inputs bell and global. Before doing above make sure all device lids are on or contacts are ok, It may be your system sees a tamper or cut wire.Above will work if the tamper came up after an electrical storm."
Tony
March 2008