JF Ptak Science Books Quick Post
It is a little difficult to get a realistic idea of how big this plane is--beyond it being really big--but by using the height of people and the stairs used to gain access to the aircraft it seems as though the height from the street/wharf to the bottom of the massive wing is at least 80'. Since this is a seaplane and there is still plane-enough below the wharf level, level, so it may well be that from the top of the wing to the water may be closer to 100'. That's a tall plane. The wingspan is more difficult to guess, but it seems as though there's room enough for a loose line of 75 people to fit under it comfortably with ample personal space, meaning that this section of the wing--probably 40% of the entire wingspan--may be on the order of 200', meaning the overall width would be in the neighborhood of 500'.
According to the technically-light description of the aircraft (found in Popular Mechanics, April 1934) this beast was meant to carry 1500 people and several hundred tons of cargo on a Transatlantic flight that would go from Southampton to New York "at a speed of 200 miles an Hour" in "less than fifteen hours".
The odd thing about this is that the imaginateers ("visioned by British Aeronautical Engineers") didn't see more powerful engines for their gigantic aircraft that could push the envelope at 350 mph. Why not? If you could give an aircraft an acre or two of thick wings, why not press the imagination a little further and assume that there would be unseen developments in powering the thing?
In any event, the artwork has a certain "Wow!" factor to it, and that someone, somewhere, was coming up with a mostly-big idea.