UK Car Repair: Auto electric short circuit, wire strands, plastic casing

Question
My question is concerning a possibility of a short circuit in the auto electrical system and is quite general in nature. The ignition key gets slightly more than warm when in use. I have replaced the barrel which incidentally is a plastic casing. It is connected to the car wiring harness via a 5-terminal female socket. The insulation of the wires and the socket have melted to an extent but still seems usable. This is the second barrel I have replaced. I am thinking of replacing the socket just in case it helps to reduce any resistance. How do I check for any possible shorting in the circuit.

Answer
Open the connector for the ignition switch loom and inspect, a loose connection, or a spade connector/bullet connector that isn't crimped properly(eg. only holding half the wire strands)will get hot.

Trace each the melted wires to their most local connection and inspect.

If all connections are good then there's a massive drain somewhere, though that would be causing problems with every system on the car. I'm pretty sure it will be a bad connection at the ignition loom connector.