MG Car Repair: 1973 MGB-GT starter problem, starter solenoid, jumper wire

Question
Ignition switch will not operate starter motor.
I can only get car to run by connecting a jumper wire(test lamp) between BROWN wire terminal and WHITE/red wire terminal on the starter relay switch(ignition ON).
I suspect a faulty relay switch but it could be starter solenoid or the ignition switch.
Starter motor w/solenoid are just a few yrs. old and seem OK and connections are OK.
Do you have a test that will pinpoint the problem as I can't afford to replace the wrong (expensive) part.

Answer
Kevin, that is why it is important to test the circuit from the ignition switch to the relay and from the relay to the solenoid.
You did not make it clear where you connected your jumper. If you connected your hot jumper to the white w/red wire on the relay and it starts, then you have tested the solenoid and the wiring from the relay to the solenoid. Also you have tested the relay, power to the relay and the relay ground. The next step is to test the white w/red wire at the ignition switch. (It is better to use a 12v test light rather than connecting a hot wire just in case there is a short some where) Just go to the column ignition switch plug connector and see if the white w/red wire gets hot when you turn the key to the start position. If it don't, the ignition switch is bad.
Let me know,
Howard