The problem could be to do with the ignition barrel, or it could be a hundred other things including a poor earth somewhere on the car. But my experience with Fords of this vintage suggests the first place I’d look would be what’s called the inhibitor switch.

This is a small switch that tells the car whether the transmission is in Park or Neutral before allowing the engine to turn over or start. If this switch isn’t relaying that information, the engine won’t so much as budge. And the fault is often intermittent.

So, try this. Instead of trying to start the car in Park, move the selector to Neutral and hit the key again. Often the inhibitor switch that isn’t recognising Park will still detect Neutral and you’ll be on your way.

The most common cause of this behaviour is a build-up of air inside the braking system. When you push the brake pedal, the fluid is forced to push on the parts of the braking system that clamps the brake pads to the brake rotors. That creates friction, and that causes the car to slow.

But the whole system relies on that pressure and it works because the brake fluid (as a liquid) can not be compressed. But air can. So, if there’s any air that has managed to enter the braking system, it will compress when you push the pedal, and the clamping force at the rotor will not be as great.

The fix is to what’s called 'bleed' the brakes. This process removes the air and should restore braking performance. In the meantime, the absolute best advice is to not drive the car anywhere while the brakes are not in top shape. The consequences are not worth thinking about.

Have the car towed to a workshop and while it’s there, think about having the brake fluid replaced as well as having the brakes bled. Fluid should be changed every couple of years but this is a somewhat ignored procedure among many car owners.

This version of the Ford 5.4-litre V8 is not universally admired by mechanics. It can tend to run hot, and it’s quite common for this unit to suffer from stretched timing chains, worn chain tensioners and guides. Any problem in the area of the timing chains can lead to a misfire or stumble, and it can be worse when the engine is hot and the oil pressure that powers the timing chain mechanisms starts to fall away.

The best advice is to have the car electronically scanned. This might pinpoint the problem by throwing up a fault code that a mechanic can decipher (including the camshaft timing fault we’re talking about). Don’t continue to throw new parts at the engine; that’s a great way to waste time and money and still not fix the problem.