Their flight path looks as though they potentially dumped some fuel. Should this be the case would they do this and then evacuate when they land? The only thing I can think of is the situation worsen as they returned.
If there was smoke in the flight deck, and they thought a return was warranted (which of course it is), why did they take the time to fly south after their departure to SAM, the only thing I can think of is to dump fuel. Surely turning around heading directly back to LGW would not have left them too little track miles to descend?