Firstly, I would congratulate the pilot for getting that aircraft down safely - in arguably the worst situation a pilot may find themselves - absolutely full marks.
Looking at the picture of the scene I question whether the fire was in fact inside. The fuel pump and a drain valve is on the lower port side of the engine compartment. I had an incident once when, after an emergency landing, fuel was found to be pouring from an ill-fitting detachable fuel bowl sited beneath the fuel pump.
I wonder whether the prop wash/air flow would cause a fire emanating from a similar event as mine to curl up and over the fuselage as it appears to have done in this case. The ignition source in this scenario would of course be the exhaust.
Just a thought.
For once, a very considered newspaper report.
wr