The original design emanated from Handley Page and subsequently became the HS146 in the early/mid 70's before (in 1978) the go-ahead was given for the BAe 146-100.
Its original design parameters were shortfield/unpaved/hot-high operations, such as at Lae, Paro, Dutch Harbor and Santos Dumont. As such it was aimed at replacing the older generations of DC3s / F27s / HS748s and a few Viscounts.
A big thing was made of the fact that the 4 ALF502s together had less rotating parts than 2 JT8's. Unfortunately this did not convince any engineering gurus, who were also aware that historically British aircraft were built like brick s**thouses with built-in quirks.
Obviously certain mission specifics gave it some market penetration (i.e. less than 800 NM, small runway, low noise profile). Nevertheless sales were slow until, to the big surprise of BAe North American carriers like PSA, AirCal, Air Wisconsin started to take an interest in the mid 80's. Also the purchase by TNT of the 146QT was a major boost. In other markets aircraft like 737/200 and -300 and DC9-50 and 80's and later the F100 had better seat-mile economics.
Lack of development in the late 80's, particularly the engine, eventually caused its demise. The RJ series, although more advanced, had negative impact due to the above. As a result numbers built would always be small. Pure economics set in, ultimately resulting in the demise of the Hatfield factory and the concentration of departments at Woodford.
No doubt the RJX would have pacified most of its critics, but alas...........A crying shame!!!!!