These cables used to be 'the end' on the wiring loom. In reality these cables are the interfacte between the component and the wiring loom.
These 'interfaces' are the same on nearly all the british biult cars from the 40ies to the 70ies.
These cables are configurated as 'pig tail'. This means, the one end fits to the component, the other end fits to the wiring loom.
The one end is fitted with a connector which fits to the headlight lamp (3 terminal FastOn connector) and the other end is fitted with the propper bullet terminals which fits exactly to the wiring loom.
This means it is very easy to change the rotten cable with a new one. Just connect the cables with the same colour to each other.
It is very advisable to change also the Bullet Connectors during this action.