Hi, I bought a new ceiling light which has the normal, neutral, live and earth connections. I have just taken down the old light bulb connection and I am totally confused.
I have three electrical cables coming out of the ceiling and I am looking at three earth wires, two red wires (old live) two black wires and a black wire which someone has put a bit of red insulation around it.
I can't seem to get the connection right, it's either constantly on and completely ignoring the switch on the wall or not working at all.
I am a major newbie and can't even remember how it was connected to the old bulb!
Help me please
Oh and I think it might be somehow connected to the light at the top of the stairs...

Sounds like you have a switch loop, two wires in one cable coming from a switch, live power needs to connect to one wire, and the other will connect the live wire of the fixture.

Blue wire on the fixture should all be connected and is the neutral.

You need to figure out which wire is live. I suspect one cable connects to live and neutral and feeds something else.

I hope this helps.

Thank you so much for taking the time to help me, can I explain at bit more what I'm looking at coming out of the ceiling...
I have three big electrical cables coming out the ceiling.
One has a red wire, a black wire and an earth.
One has only a black wire and an earth
One has a red wire, an earth and a black wire (which someone has put a red loop of wire on)
I have tried loads of variations but can only seem to get either constant on or not working...

Thanks so much, thanks to you saying swithc loop, I looked up the diagram and it would appear this is what it is, the black wire with the red flex on signifies the switch wire, (learn something new every day!) I can now trun the light on and off but the dimmer doesn't work, (it was working before I started messing about!)
Any thoughts?

I did the best I could , the color code you have tells me your not in North America, and I don't know others codes and methods, so much.

Sounds like you have managed.

If you were doing any connecting of wires while energized, or if there was a short circuit, the dimmer easily could had been damaged.

Be sure all connections are tight.

Never connect dimmers, esp the electronic ones, live.