Alarm problems

[Maker222]

Hi everyone, Hope someone can help, My car is a XKR 2009 and I have this high pitched sound coming from the righthand wing area in the back corner. This happens about 5 minutes after the car is locked, even if I leave the car unlocked within 5 minutes the high pitch sound starts. I have tried to remove different fuses to stop this noise but nothing works, the only way I have found to stop it is to disconnect the battery,