Apparently it was designed as a 727 size A/C but B.E.A. (British European Aiways) decided it was too big and insisted it was re-designed to their specifications. The result was non too successfull, great at coming down but required the curvature of the earth to get airborne and had a poor range.
Many of the folk I have flown with still shed a tear at the mention of the word 'Trident', it was B.E.A. you see.
Regards
Exeng