A preliminary report within one week of the accident is a sensational effort
It is indeed, but I venture to suggest that the proximity of the accident to their base has probably been a factor. I've seen a pic online that suggests the rising smoke at EGLK was clearly visible from EGLF. They would have been on site very quickly, one suspects.
Apparently, Border Force were awaiting the Phenom's arrival, and had to ask locals who observed the accident whether it was the a/c they had been waiting for.