I certainly remember the 128 as having a far better engine than most of its rivals. The 1.3 Viva/Chevette engine was quite asthmatic once you started to make it work; the 1.3 Escort/Cortina unit wasn't much better, and neither was the motor in the Sunbeam/Avenger.
It would rev far more easily and far more strongly than its competitors, and unlike many wasn't prone to "hunting" when you came across slow moving traffic or overheating.
My memories are that it rode quite well, was a strong performer and was comfortable for passengers, although I only had a saloon, but the version your mum had was rarer than the saloon and, despite only having 2 doors was probably much more flexible.
Nice period grainy photo there. An analog car in an analog photograph. Eeee, them were t'days..............