Why design a passenger aircraft with a high wing?

[Jig Peter]

@Safety Pee (post 31)

Thread drift here - sorry - but you're a bit off-beam about any A300/BAC311 link.
In the "original" Airbus studies, British participation was largely from Rolls, with Hawker Siddeley to do the wing. Vickers/BAC were not involved in the least, but later came up with the rival 311 which got nowhere when the government of the day would only support (tepidly?) one big civil airliner project, plus the RB211 for the 1011.
Rolls were offering fantastic thrust levels (for the day) from their big 3-shaft fan engines, to match the then A300's DC-10-width fuselage ("Grosse Julie"). When Rolls turned their attention to the lower power needs for the Lockheed 1011, they left the A300 as it then was, powerless.
Airbus, under Roger Beteille, then turned to GE whose CF6 was being developed to a thrust level suitable for a higher AUW version of the DC10, and at the same time reduced the fuselage diameter to the 222-inches which became the "standard" Airbus wide-body size, and thus the "old" A300 became the A300B, with HSA's wing.