Photocell rewiring

[jepelite]

Hi - hoping someone can help me please. Whilst removing ivy from the gatepost I have accidently pulled the wires out of the photocell (the receiver I think). Knowing nothing about electric gates I would really appreciate some advice on how to rewire it. I've attached a couple of pictures showing the wires and inside the photocell. Unfortunately, we didn't install the gate and the previous owners left us no paperwork so we don't know the make and can't see any thing to indicate it anywhere.

Any help/advice would be much appreciated.