A serious answer to this question?
For me, probably scaling down HS Trident 1 (DH 121) to meet the BEA requirement. Boeing were terrified of the original spec Trident 1, as it would've done very nasty things to the 727 (1831 built); instead, BEA insisted on a smaller, less capable aircraft and the result was Trident 1, 2, 3 - a total of 117 built.
S41