My Jaguar Xtype 2L diesel 05 wont start in the mornings. Had new alternater and battery put in. Garage changed fuse and got all the computer back up and running but this morning again it wont start! put jump leads on and alarm on car went off before managing to get it started off other car battery.

Sounds like you have a current drain on the battery even when switch off. With the ignition off put a ammeter between the negative lead and the negative terminal of the battery and measure the current drain. If detected now remove and reinsert each fuse in turn noting the change in current flow. By this process you will isolate the offending circuit. Interior glove-box or trunk lights can be the very devil since like a fridge light you can never tell if they go off when they should.