SaturnV wrote "But the summary presumes that the captain is able to re-enter the cockpit by himself. If he cannot, would you not think that the BEA would note that the PNF had to leave his seat to open the door for him at a most critical time in the flight? "
With the importance of the words and actions of PF & PNF it seems inconceivable that the BEA would not note PNF arising from his seat and allowing the Captain to enter the flight deck.
Any such action would impact upon the focus PNF would have (I assume it would be he) on the developing situation.
Unless there was a third party on the flight deck able to do open the door or the Captain had a way to enter that did not require the intervention of PF/PNF?
Someone occupying seat four on the flightdeck?
The BEA should have addressed this issue in the report - stating just who was on the flight deck - for the avoidance of doubt and speculation. Their raising of seat four from the crash site has indicated some issue that needed to be investigated.
It would not be out of place for them to address this matter now.