It may be the switch that actually doesn't allow the car to start unless the clutch pedel is depressed.
Get in the car, and press the pedel down, but stop before you hear the click, and try and start the car. It should not start if you haven't heard this click.
Now try again, but this time depress the clutch, and as soon as you hear the click, try to start the key. If it starts this time then it's just the button that you're hearing.