Can't help thinking that Shorts flying boat experience was making too much of a penalty in terms of the internal layout.
Even allowing for Imperial Airway's lavish tastes and the fact that lounges etc. could still be found on American large airliners until 1970 (747), the space required for 12 passengers seems rather excessive. So does the flight deck, there is acres of workspace for the navigator, radio oeprator and engineering and even a rest station/bunk, which seems lavish.
The competing Airspeed and Folland designs seem more like a 'cram-em-in' approach with a respectable passenger capacity and perhaps some chance of operating at an economic level.