No criticism of the fire crew or procedures here. An unattended aircraft caught fire. I regard that as serious.
I'm glad to see, (as I expected,) that the AAIB will be heading up the investigation. Their report will be both thorough and made available to the public so whatever the truth, we shall be told it. (Anathema to a rumour network, I know but preferable to a
Boeing press statement that would not be trusted by many.)