This lovely aircraft was the losing competitor of the Vickers Viscount for the Type II civil transport (a short- and medium-range airliner for European routes) requirement outlined by the wartime Brabazon Committee. Both designs shared a quite similar bulbous fuselage shape and needle-like turboprop engines; RR Dart for the Viscount and AS Mamba for the Apollo. It was precisely those troublesome Mambas the main cause of Apollo’s nemesis. Only two prototypes were built and flown.
Pretty inflight photo of the first prototype. Cute, isn’t it?