The Arrow range was conceived to be a conventional replacement for the Audax Rootes cars – and as such, was designed in Hillman, Humber and Singer versions. The early styling schemes resembled an enlarged Imp, but these were soon revised into a plainer and more classical looking saloon.
Late in 1963, a simpler car (than the Swallow) was conceived; one that would be cheaper to develop, and cheaper to produce. The smart “Arrow” was the result, and thanks to the above work on the earlier car, the style was adopted and accepted remarkably quickly. These full-size models were approved by management on April 17th 1964.
With thanks to Roy Axe for clarifications