extractor fan switch

Hi, I am after some advice please. We have an extractor fan in the bathroom operated with a ceiling switch - installed about 20 years ago. The switch started sticking a while ago and eventually gave up all together, when I unscrewed it the inner connections came away in bits - corroded.

The switch is a MK Logic Ceiling 16 Amp 1 Way DP Pull Switch - mounting block with neon. I have got replacement for these. The switch has load and supply with live and neutral marked connectors. The cables are red, blue and yellow. Because of the state of the original switch I cannot say with certainty which colour went where. Searching for these colours on line mentions three-phase wiring but I cannot find anywhere explaining how to wire the switch correctly.

Any advise appreciated.

 

Thanks for the info - looks like I will have to head into the loft. Closer inspection of the two sets of cable coming into the mounting block only one has all three colors - the other has only the red and blue with the yellow looking like it has been snipped at the shield. So need to check exactly what is going where.

From memory as parts of it fell away I thought the two blue where in the same connector which if I understand you correctly would make this the permanent live. If so I may be better giving someone qualified an easy job than have a go myself.