hello

bought a 2 way 2core through switch with no instructions and aren't sure how to wire it.  also might have lost a piece unpacking it.

questions (see diasgram on gallery image)
1) are there supposed to be 3 or 4 brass screws for connecting wires in the item? i have them at A. B and C but not D where the plastic mould has room for one.

2) if 3 then where do the brown and blue wires go?
eg: blue in & blue out both to the same screw?

a simple thing with many possibilities. any help apppreciated.

How many actual switches does the switch have?. It looks like a 1 switch (1g) switch e.g. common, L1, and perhaps an earth lug or something if it's metal.

The picture doesn't appear right now in your reply, but picture is below. If you have just 2-core flex in and out then you need to wire it as per revised image below. Brown wire from the mains plug in one end of the switch to A, then you wire the brown wire going out other end of switch to your light. The C connection is where you connect both your blue wires, one from plug, one to light. D is where there would normally be an earth connection, but that doesn't apply to you if you have only 2-core cable.

If your fitting is brass/metal then it ought to have an earth wire (green/yellow) and 3-core cable as opposed your 2-core cable.

Hope this helps.