It and Vanguard, are, I think, the sole wholly privately-funded civil types that the industry has attempted.
And Percival Merganser/Prince surely, didn’t think that came from an MoS (or other) spec?
It strikes me that the Prince and Concordia were just to similar for a fairly restricted market, AUW, dimensions and engines almost identical, the Prince had the advantage of a much handier layout and full aircraft company behind it though.