Four black wires in ceiling socket

[Moonraker]

A rose in my 1970s kitchen ceiling became loose (one fixing screw had been inserted right on the edge of the hole in the ceiling) and when I removed it I was faced with a jumble of wires.The green & yellow one was attached to the earth terminal in the rose, four red wires were twisted together and still secured to the terminal in the bulb socket, as was one black wire into another terminal. Another black wire was loose, and two more black wires had their ends bent up into hooks and presumably had never been attached (???).

I have no lighting in the room next door. (I am vaguely aware of circuits.)

Do I secure the loose wire into the third terminal in the socket? And does it matter which wire goes into which terminal (one is slightly taller than the other two)?

 

[westward10]

A pic would help.

 

[Moonraker]

 

[westward10]

I think you are going to need an electrician as from afar we aren't going to be able to assume which of those should or shouldn't if not all should be connected.