Can we settle this question of who was PF and which seat he was occupying?
According to press reports, the junior FO (800 hrs on type) was PF, having been designated as such by the captain. But where does this idea come from?
According to BEA's 27 May update, "at 0155 the Captain woke the second co-pilot and said '[...] he's going to take my place'".
The 'second co-pilot' presumably was the junior FO.
Who was 'he'? Presumably, it was the junior FO and it seems highly likely that he was going to physically take the place of the captain in the LHS. However, that does not necessarily mean that he was PF.
I would instinctively think, as they were approaching an area of turbulence, the captain would designate the more experienced, senior FO (4400 hrs on type) as PF.
Yet, one minute before they impacted the sea, "the PF said 'go ahead you have the controls'. It seems unlikely that a more experienced pilot would hand off to a less experienced one.
So I would think the junior FO was PF and the senior FO was PNF.
Of course, there's also the possibility that, after he returned to the flight deck, the captain changed places with the senior FO in the RHS...but that's hardly likely.
I suppose the question can easily be settled by the BEA.