in the boot by the spare wheel, theres a small siren thingy
Thats the one! I assume the beeps come from the siren (alarm?), if it's not a common problem then looks like I shall be a pioneer.
Everything looks good, so water shorting somthing is out of the question. I'm thinking it's just circuit died... or a loose wire. I'm hoping for the latter.
thats right it uses the alarm siren, does the alarm work ? is your reversing light working ? iirc they take the wires from the reverse light to act as a switch for the buzzer and sensors