As these two planes were the only two affected, and they both went down in similar fasion, I am also leaning in the direction of a deliberate act. My brother and I lost a scale Hawker hurricane to a deliberate act from a police car. The two officers denied any involvment at the field, but where overheard to admitt it after a few drinks at a local watering hole. They "just wanted to see what would happen", as they said. Serve and 'protect'?

This was years ago, but I still can't rule out this senerio.