From the interim AAIB report I've gleaned the following facts:
The crew felt vibration which they thought might be the nose wheel running over the lights on the runway during the take off roll.
ATC reported to them that debris had been found on the runway.
They had a failure of the yellow hydraulic system and a significant fuel leak.
They had an indication of a fire warning on the right (no2) engine and upgraded their PAN to a MAYDAY.
Lastly, and here's the most important item, IMHO, the left engine continued to OPERATE NORMALLY.
By the way the Commander had 14337 hours of which 8036 are in type. That's quite a few LPCs under his/her belt not to mention years on the line. I said before "well done" and still see nothing except, perhaps, the issue of the walk round to criticise them. As others have said the walk round is frequently done with numerous doors/hatches still open.