Ah, nostalgia!
I saw this beast many times back in the day whilst spotting at LHR, but can't say I ever noticed the 'bump' just after the main hump joins the fuselage. What was inside ? These days such protrusions are commonplace, but back then they were somewhat rare.
Aslo, thread-drifting, that TMA 747 reminded me that I'd forgotten that they had the type at all, MEA yes, but I only remember seeing TMA 707's. Perhaps I'd discovered girls and had taken my eye off the ball ;-)