Storage Heater Wiring

[taff1]

When on, the 20amp switch, connecting the heater to the off-peak power supply, feels quite warm. I've checked that all the connections are correctly made and found everything AOK. I think it is the neutral wire (blue) connecting the switch to the heater that is the problem, it appears to be changing colour.
What is going on ?

 

[RF Lighting]

Possibly a worn contact inside the actual switch front.

If the neutral has changed colour this is a sign of over heating which may have damaged the copper aswell. This should be cut away and reterminated onto a new switch.