The fire theory was ruled out in its day. It would have made White Star guilty without question.
What gives the fire theory (real fire but questionable cause for ultimate sinking) a bit more inertia is a never before submitted photo of the burned paint on the hull from the outside before the voyage began. The second cooberating factor is from today's fire forensic engineers whose results show internal bulkhead warpage similar to what old time witness' testified to seeing.

Like the Warren Commision I can only assume that the fix was in from day one of the Titanic Commission. My bias proves nothing.