Baffled By Lamp Wiring

Apologies for the possible stupidity of this question. I think i may gave posted this in the wrong forum earlier.

I've just moved house and thought I'd put up a wall light in the porch. There was a light there but I don't know if it ever worked.

There are three cables:

Cable A: has live (brown), neutral (blue) and earth wires. I tested this cable with a circuit tester and this is live.

Cable B: has live, neutral and earth wires. The circuit tester doesn't show a response for this.

Cable C: has a live and earth wire. No neutral wire.

I tried connecting the wires from Cable A to the respective wires in the new lamp. I have a lamp that's permanently on.

If I try any wiring the lamp to Cable B then nothing happens.

Any hints for what I try next are welcomed and appreciated. Many thanks

Cable C most likely does have a Neutral wire, but its been snapped or cut off. For future take a picture before and during doing connections,

Cable B is most likely the switch. Connect the Brown of A to the brown of B in a connector block. The blue of A is the neutral( N)  and the blue of B is  the live (L )  to the light which should have a brown bit of tape put on. Make sure its ALL TURNED OFF FIRST. Cable C i dont know so try my idea. Insulate C whilst you try

Brilliant!! Worked a treat. Thanks ever so much.