Anyhow - we were up front in seats 4D & F. I wondered about seat 4E, but it was a narrow area with a seat belt, but I don't think you could put anyone in it. I wonder what it's there for?

These are convertible seats - if the section you were in had been Economy instead of Club Europe - the E seat would widen into a standard sized economy seat.

You were defintely on a 767 then.