NASA news conference said that one of the indepentent enquiry boards formed of people from outside NASA is appointed before every shuttle flight. Therefore, my speculation that twenty minutes was too short a time to put together soch a group and get it working was wrong. My apologoies to all concerned.
Discussion in the conference on debris coming off the main tank was on foam rather than ice coming loose. The foam may have impacted the underside of the left wing somewhere between the wing tip and half way between the tip and the root causing an undetermined amount of damage. Loss of sensor readings and rising temperature readings in the final minutes all came from the left wing and left landing gear area.
This damage by the foam looks as though it may have happened too late in the launch (over the ocean) for the detached tiles to have been recovered and the damage assessed that way.
