Originally Posted by
Shaggy Sheep Driver
The criticism of dH is that they let BEA talk them out of the Medway engined dH 121 and instead build the ludicrously small 90 seat Trident 1 for which the Spey sufficed.
One must understand that in 1960. when the Trident was being designed, 90 seats was not small, but large, for BEA European services, these had commonly low load factors (60-70%) as it was with the Viscount which preceded them on many routes. The bigger Vanguard had sold on the basis of seat-mile costs, but the bums on seats to cover all those Vanguard seats just weren't there except on a few domestic trunk routes (which the Trident, initially, was not expected to cover).
The standard aircraft of the era for many of the BEA competitors into London was the Caravelle, which had less than 90 seats. With the pooling arrangements of the era with most other European flag carriers, the more seats your aircraft had, the less frequency you could do, needing to maintain a strict seating balance.