The further the Fifties progressed, the tougher it seemed to get for Armstrong Siddeley.

Although the Sapphire series had been in production for more than four years, sales have failed to take off, with the possible exception of the most substantial version of the three, the 346, with sales figures that were almost respectable.
That scrap of relative success in an ever competitive market may have caused the Armstrong Siddeley management in 1958 to believe that they had finally found the direction and followed their instincts with the launch of the Star Sapphire in October of that year.
As far as powertrain was concerned, the design team at Armstrong Siddeley continued to specify a six-cylinder engine for the Star Sapphire, although enlarging it considerably, by more than 16% to 3,990 cc with larger twin Stromberg carburettors fitted as standard.
This combination meant that the Star’s power output was pushed up to 165 bhp, and the car was capable of reaching speeds of  104 mph (167 kph).

The company’s efforts were at least appreciated by the motor industry, with the Star Sapphire being awarded first prize in the four-door coachwork category for cars with a price tag in excess of  £4,000 at the 1958 Earls Court Motor Show.
To win the prize the Star Sapphire had to beat out such strong competitors as Austin with their Princess limousine and Jaguar with their iconic Mark IX.
Unfortunately, time was running out for Armstrong Siddeley who had been in a loss-making situation for too many years. In 1960, the company management made the brave decision to wind the business up.