I have an update on this problem ...for anyone interested
I charged the battery to 100%, reconnected it and we still had the same problems (Central locking and Alarm), so I decided we needed a new battery (it is over 4 years old).
I bought a new battery, a good quality Bosch S5. When I came to fit the new battery I rechecked the old one. The old one had dropped from 100% to 57% and it had not gone anywhere. So I thought at least the new Battery was needed.
I fitted the new battery, reconnected and still had the Central locking and alarm issues
So we gave up and checked it in to a specialist.
Three days later, my wife tried the central locking again and the darned thing worked properly !
Today (Sunday) I put the new battery on charge ... and it took 4 hours to reach full charge !
I reconnected, and again all systems seem ok.
So, puzzled. It might appear that there is some other system on the car that needed charging up perhaps???
So the old battery was not good enough to keep things charge, but after 3 days the new one was ?
Sounds mad ,,,,,,
We still have the car booked into the specialist for a week tuesday should this madness return.
But for now the problem has gone away.