help re ceiling rose for 2 way switch light

[caro]

I removed a ceiling light fitting and the wires in the ceiling are gathered in groups to connectors and covered in tape I am loathe to remove. The three groups intended to go into the rose are earth (obvious), a bunch of all red wires in one connector and one black with a yellow sheath on it.

In all the diagrams I have seen the wiring is switch to switch to rose and the yellow link wire does not go to the rose. I wonder if this system is switch to rose to switch as both switches are on opposite side of a small hallway with the rose in between them, not up and down a staircase.
There is no black-flagged-red.
Any suggestions as to where I should put these three sets of wires in the rose would be gratefully received as trying to figure it out any more does not seem to produce results.
PS It worked fine before I took off the old chandelier thing!.

Caro.

 

[ban-all-sheds]

Do you have any means of testing which wires are live, and when?

 

[caro]

I have never used a tester with 2 probes but I have got a screwdriver type with a brass top. It sounds like I would need to get behind all the connectors? or maybe not all, I need is to find out which combination gives me a current, I suppose.